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[Powered by Google Translate] [Wiki 6, Inaendelea]

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[David J. Malan] [Chuo Kikuu cha Harvard]

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[Hii ni CS50.] [CS50.TV]

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Hii ni CS50 na hii ni mwisho wa wiki 6.

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Hivyo CS50x, moja ya kozi Harvard ya kwanza ya kushiriki katika mpango edX

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kweli hii ilipata kushika nafasi ya Jumatatu iliyopita.

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Kama ungependa kupata glimpse ya wengine ni nini kwenye Internet

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sasa kufuatia pamoja na, unaweza kichwa kwa x.cs50.net.

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Hiyo redirect wewe kwa sehemu husika kwenye edx.org,

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ambayo ilikuwa ambapo hii na kozi nyingine kutoka MIT na Berkeley sasa kuishi.

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Itabidi kuingia kwenye akaunti; utapata kwamba ni nyenzo kiasi kikubwa sawa

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kama umeshapata hii muhula, angalau wiki chache kuchelewa, kama sisi kupata kila kitu tayari.

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Lakini nini wanafunzi katika CS50x sasa kuona ni interface kabisa kama hii moja.

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Hii, kwa mfano, ni Zamyla kuongoza walkthrough kwa tatizo kuweka 0.

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Juu ya kuingia katika edx.org, mwanafunzi CS50x anaona aina ya mambo

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gani wanatarajia kuona katika mwendo: hotuba kwa Jumatatu,

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hotuba kwa Jumatano, mbalimbali kaptula, seti tatizo, walkthroughs, PDFs.

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Aidha, kama unaweza kuona hapa, mashine Tafsiri

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wa nakala ya Kiingereza ndani ya Kichina, Kijapani, Kihispania, Kiitaliano,

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na rundo zima la lugha nyingine ambayo hakika kuwa si mkamilifu

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kama sisi roll yao nje programmatically kutumia kitu kinachoitwa API,

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au maombi ya programu interface, kutoka Google

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ambayo inaruhusu yetu kubadili Kiingereza kwa lugha hizi nyingine.

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Lakini, shukrani kwa roho ya ajabu ya kujitolea baadhi mia-plus,

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random watu kwenye mtandao ambao kindly inayotolewa kujihusisha

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katika mradi huu, tutaweza kuwa na kuboresha hatua kwa hatua ubora wa tafsiri wale

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kwa kuwa binadamu kusahihisha makosa kwamba kompyuta yetu kuwa alifanya.

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>> Hivyo zinageuka tulikuwa wachache zaidi wanafunzi show juu ya Jumatatu kuliko sisi awali inatarajiwa.

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Kwa kweli, sasa ina watu 100,000 CS50x kufuatia pamoja nyumbani.

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Hivyo kutambua wewe ni sehemu ya darasa hili uzinduzi wa kufanya kozi hii katika sayansi ya kompyuta

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elimu kwa ujumla zaidi, pana zaidi, kupatikana.

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Na ukweli ni sasa, na baadhi ya kozi hizi kubwa online,

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wao wote kuanza na nambari hizi juu sana, kama sisi tunaonekana kuwa na kufanyika hapa.

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Lakini lengo, hatimaye, kwa CS50x ni kweli kupata watu wengi kama mstari wa kumaliza iwezekanavyo.

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Kwa design, CS50x anaenda kutolewa kutoka Jumatatu hii iliyopita

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njia zote 15 Aprili 2013, ili folks ambao wana ahadi shule mahali pengine,

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kazi, familia, migogoro mengine na kama, kuwa na kidogo zaidi kubadilika

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na ambayo kwa kupiga mbizi katika kozi hii, ambayo, inatosha kusema,

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ni kabisa ambitiously kufanyika kama tu juu ya mwendo wa miezi mitatu tu wakati wa muhula wa kawaida.

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Lakini wanafunzi hawa itakuwa kukabiliana seti tatizo moja, viewing maudhui sawa,

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kuwa upatikanaji wa kaptula sawa na kama.

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Hivyo kutambua kwamba sisi wote ni kweli katika hii pamoja.

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Na moja ya malengo ya mwisho wa CS50x si tu kupata folks kama wengi

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mstari wa kumaliza na kuwapa ufahamu huu newfound wa sayansi ya kompyuta

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na programu lakini pia kuwa na wao wana uzoefu huu pamoja.

46
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Moja ya tabia kufafanua wa 50 juu ya chuo, ni matumaini yetu,

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imekuwa ya aina hii ya uzoefu wa jumuiya, kwa bora au mbaya, wakati mwingine,

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lakini baada ya kuwa watu hawa kurejea kwa kushoto na kulia,

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na ofisi ya masaa na hackathon na wa haki.

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Ni ngumu kidogo kufanya hivyo katika mtu na folks online,

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lakini CS50x tutahitimisha katika Aprili na Expo kwanza milele CS50,

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ambayo itakuwa kukabiliana online ya wazo yetu ya haki

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ambapo hizi maelfu ya wanafunzi wote wataalikwa kuwasilisha 1 - 2 na video ya dakika,

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aidha screencast ya mradi wao wa mwisho au video wao akipunga hujambo

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na kuzungumza kuhusu mradi wao na demoing yake,

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kiasi kama watangulizi wako wamefanya hapa juu ya chuo katika haki,

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hivyo kuwa na mwisho wa muhula, matumaini ni kuwa na maonyesho ya kimataifa

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wa miradi ya wanafunzi CS50x 'mwisho, kiasi kama yale zakulaiki hii Desemba hapa juu ya chuo.

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Hivyo zaidi juu ya kwamba katika miezi ijayo.

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>> Pamoja na wanafunzi 100,000, ingawa, huja haja ya CAS chache zaidi.

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Kutokana na kwamba wewe guys ni mkali uchaguzi hapa na kuchukua CS50

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wiki kadhaa kabla ya kutolewa nyenzo hii kwa folks juu ya edX,

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kutambua upendo tunataka kuhusisha kama wengi wa wanafunzi wetu wenyewe kama inawezekana katika mpango huu,

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wote wakati wa muhula kama vile baridi hii na hii spring ijayo.

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Hivyo kama ungependa kushiriki katika CS50x,

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hasa juu ya kujiunga katika CS50x Diskutera, toleo edX ya CS50 Diskutera,

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ambayo wengi wenu wamekuwa kutumia juu ya chuo, online bulletin bodi,

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tafadhali kufanya kichwa kwa URL kwamba, hebu kujua wewe ni nani,

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kwa sababu tunatarajia upendo wa kujenga timu ya wanafunzi na wafanyakazi na kitivo sawa

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juu ya chuo ambao ni tu kucheza pamoja na kusaidia nje.

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Na wanapo kuona swali hilo ni familiar nao,

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wewe kusikia mwanafunzi kuripoti baadhi mdudu mahali fulani huko nje katika nchi baadhi ya mtandao,

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na pete kengele kwa sababu wewe pia alikuwa na kwamba suala hilo hilo

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katika yako d-hall baadhi ya wakati uliopita, hopefully basi unaweza chime katika na kubadilishana uzoefu wako mwenyewe.

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Hivyo tafadhali wanayo haki kama ungependa.

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>> Kompyuta kozi ya sayansi katika Harvard kuwa na kidogo ya mapokeo,

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CS50 kati yao, ya kuwa na baadhi ya mavazi, baadhi ya nguo, kwamba unaweza kuvaa kujigamba

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mwishoni muhula, kwa kusema kabisa kujigamba kwamba wewe kumaliza CS50

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na alichukua CS50 na kama, na sisi daima kujaribu kuhusisha wanafunzi

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katika mchakato huu kama iwezekanavyo, ambapo sisi kuwakaribisha,

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karibu wakati huu wa muhula, wanafunzi kuwasilisha miundo

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kutumia Photoshop, au chochote chombo cha uchaguzi Ningependa kutumia

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kama wewe ni designer, kuwasilisha miundo kwa ajili ya fulana na mashati

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na miavuli bandanas kidogo na kwa ajili ya mbwa na sisi sasa kuwa kama.

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Na kila kitu ni basi - washindi kila mwaka ni basi exhibited

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kwenye tovuti kozi ya saa store.cs50.net.

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Kila kitu ni kuuzwa kwa gharama huko, lakini tovuti anaendesha tu yenyewe

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na inaruhusu watu kuchagua rangi na miundo kwamba wao kama.

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Hivyo nimeona tunatarajia kushiriki tu baadhi ya miundo ya mwaka jana

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waliokuwa kwenye tovuti hii badala ya moja hapa, ambayo ni mapokeo ya kila mwaka.

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"Kila siku mimi nina Seg Faultn" ilikuwa moja ya maoni mwaka jana,

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ambayo bado inapatikana huko kwa Mbegu.

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Tulikuwa na hii moja, "CS50, Ilianza mwaka 1989."

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Moja ya Bowdens yetu, Rob, ulikuwa maarufu sana mwaka jana.

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"Timu ya Bowden" alizaliwa, design hii ilikuwa in, miongoni mwa wauzaji wa juu.

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Kama ilikuwa hii moja hapa. Watu wengi walikuwa "Bowden Homa" kulingana na magogo ya mauzo.

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Kutambua kwamba kwamba inaweza sasa kuwa design yako huko, juu ya mtandao.

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Maelezo zaidi juu ya hili katika tatizo inayofuata inatoa kuja.

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>> Moja zaidi chombo: umeshapata baadhi yatokanayo na hopefully sasa

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baadhi ya uzoefu wa mikono juu na GDB,

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ambayo ni, bila shaka, debugger na utapata kuendesha

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mpango wako katika ngazi ya haki Asili, kufanya nini aina ya mambo?

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Je GDB basi wewe kufanya?

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Yeah? Nipe kitu. [Mwanafunzi jibu, unintelligible]

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Nzuri. Hatua katika kazi, hivyo si tu kuwa na aina kukimbia

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na kuwa na pigo mpango kupitia ukamilifu wake, kuchapa nje ya mambo ya pato standard.

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Badala yake, unaweza hatua kupitia line hiyo kwa mstari, ama kuandika ijayo

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kwenda mstari kwa mstari kwa mstari au hatua kwa kupiga mbizi katika kazi, kawaida moja kwamba aliandika.

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Nini kingine haina GDB basi wewe kufanya? Yeah? [Mwanafunzi jibu, unintelligible]

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Magazeti vigezo. Hivyo kama unataka kufanya kujichunguza kidogo ndani ya mpango wako

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bila ya kuwa na mapumziko kwa kuandika kauli printf kila mahali,

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unaweza tu magazeti variable au kuonyesha kutofautiana.

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Nini kingine unaweza kufanya na debugger kama GDB?

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[Mwanafunzi jibu, unintelligible]

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Hasa. Unaweza kuweka breakpoints; unaweza kusema mapumziko utekelezaji

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katika kazi kuu au kazi foo.

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Unaweza kusema mapumziko utekelezaji katika mstari wa 123.

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Na breakpoints ni mbinu kweli nguvu

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kwa sababu kama una maana ya jumla ya ambapo tatizo lako

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pengine ni, huna kupoteza muda wanazidi kupitia ukamilifu wa programu hiyo.

121
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Unaweza kimsingi kuruka haki pale na kisha kuanza kuandika -

122
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wanazidi kupitia kwa hatua au ijayo au kama.

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Lakini samaki na kitu kama GDB ni kwamba inasaidia wewe, binadamu,

124
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kupata matatizo yako na kupata Bugs yako.

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Haina lazima kupata yao sana kwa ajili yenu.

126
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>> Hivyo sisi ilianzisha nyingine siku style50, ambayo ni fupi ya mstari amri chombo

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ambayo inajaribu stylize code yako kidogo zaidi cleanly kuliko wewe, binadamu, wanaweza kuwa na kufanyika.

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Lakini, pia, ni kweli tu kitu aesthetic.

129
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Lakini zinageuka kuna chombo hiki nyingine iitwayo Valgrind, ambayo ni kidogo zaidi arcane kutumia.

130
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Pato lake ni atrociously cryptic katika mtazamo wa kwanza.

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Lakini ni ajabu muhimu, hasa sasa kwamba sisi ni saa sehemu ya muda

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ambapo wewe ni mapya kwa kutumia malloc na mgao nguvu kumbukumbu.

133
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Mambo yanaweza kwenda kweli, kweli makosa haraka.

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Kwa sababu kama wewe kusahau huru kumbukumbu yako, au wewe dereference baadhi pointer null,

135
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au wewe dereference baadhi pointer takataka, ni nini dalili ya kawaida kwamba matokeo?

136
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Seg kosa. Na wewe kupata faili hii ya msingi ya baadhi ya idadi ya kilobytes au megabaiti

137
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kwamba inawakilisha hali ya kumbukumbu ya mpango wako ilipokwama,

138
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lakini programu yako hatimaye seg makosa, segmentation kosa,

139
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ambayo ina maana ya kitu mbaya kilichotokea daima karibu kuhusiana

140
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kwa makosa yanayohusiana na kumbukumbu kwamba alifanya mahali fulani.

141
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Hivyo Valgrind husaidia kupata mambo kama hayo.

142
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Ni chombo kwamba wewe kukimbia, kama GDB, baada ve compiled mpango wako,

143
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lakini badala ya kuendesha programu yako moja kwa moja, wewe kukimbia Valgrind

144
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na wewe kupita kwa hiyo programu yako, kama wewe kufanya na GDB.

145
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Sasa, matumizi, ili kupata aina bora ya pato,

146
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ni kidogo kwa muda mrefu, hivyo haki pale atop ya screen utaona Valgrind-v.

147
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"-V" karibu ulimwenguni kote ina maana verbose wakati unatumia programu kwenye kompyuta Linux.

148
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Hivyo ina maana mate nje data zaidi kuliko wewe nguvu na default.

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"- Leak-kuangalia = kamili." Hii ni kusema tu hundi kwa uvujaji wote inawezekana kumbukumbu,

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makosa ili nipate kuwa alifanya. Hii pia, ni dhana ya kawaida na mipango ya Linux.

151
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Kwa ujumla, kama una mstari amri hoja kwamba "kubadili",

152
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kwamba walidhani kubadili tabia ya mpango wa, na ni barua moja,

153
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ni-v, lakini kama hiyo ni switched, tu kwa kubuni programu,

154
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ni neno kamili au mfululizo wa maneno, mstari amri hoja huanza na -.

155
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Hizi ni baadhi tu ya binadamu makongamano, lakini utaona yao inazidi.

156
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Na kisha, hatimaye, "a.out" ni jina kwa ajili ya mpango holela katika mfano huu hasa.

157
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Na hapa ni baadhi ya pato mwakilishi.

158
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>> Kabla ya sisi kuangalia nini kwamba tupate maana, nivuke kwa snippet ya maadili ya juu hapa.

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Na napenda hoja hii nje ya njia, upesi,

160
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na hebu tuangalie memory.c, ambayo ni mfano huu mfupi hapa.

161
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Hivyo katika mpango huu, napenda kuvuta kazi na maswali.

162
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Tuna kazi kubwa ambayo inatoa wito kazi, f,

163
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na kisha nini f kuendelea kufanya, kwa Kiingereza kidogo kiufundi?

164
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Nini f kuendelea kufanya nini?

165
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Vipi kuhusu mimi itabidi kuanza na mstari 20, na mahali nyota Haijalishi,

166
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lakini mimi itabidi kuwa thabiti hapa na hotuba ya mwisho.

167
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Nini mstari 20 kufanya kwa ajili yetu? Upande wa kushoto. Tutaweza kuvunja chini zaidi.

168
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Int * x: nini kwamba kufanya?

169
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Sawa. Ni kutangaza pointer, na sasa hebu kuwa hata zaidi ya kiufundi.

170
00:10:04,940 --> 00:10:10,230
Ina maana gani, sana concretely, kutangaza pointer? Mtu mwingine?

171
00:10:10,230 --> 00:10:15,050
Yeah? [Mwanafunzi jibu, unintelligible] Too mbali.

172
00:10:15,050 --> 00:10:17,060
Hivyo wewe ni kusoma kwa upande wa kulia wa ishara sawa.

173
00:10:17,060 --> 00:10:20,290
Hebu mkazo tu upande wa kushoto, tu juu ya int * x.

174
00:10:20,290 --> 00:10:24,700
Hii haina "kutangaza" pointer, lakini sasa wacha kupiga mbizi katika undani kwa ufafanuzi huo.

175
00:10:24,700 --> 00:10:28,330
Je, hiyo concretely, kitaalam maana? Yeah?

176
00:10:28,330 --> 00:10:31,940
[Mwanafunzi jibu, unintelligible]

177
00:10:31,940 --> 00:10:35,090
Sawa. Ni kuandaa kuokoa anuani katika kumbukumbu.

178
00:10:35,090 --> 00:10:40,680
Nzuri. Na hebu kuchukua hatua hii moja zaidi; ni kutangaza variable, x, hiyo ni 32 bits.

179
00:10:40,680 --> 00:10:44,440
Na mimi najua ni 32 bits kwa sababu -?

180
00:10:44,440 --> 00:10:47,390
Siyo kwa sababu ni int, kwa sababu ni pointer katika kesi hii.

181
00:10:47,390 --> 00:10:49,650
Bahati mbaya kuwa ni moja na sawa na int,

182
00:10:49,650 --> 00:10:51,970
lakini ukweli kwamba kuna nyota kuna maana ya hii ni pointer

183
00:10:51,970 --> 00:10:57,300
na katika appliance, kama na kompyuta wengi, lakini si wote, kuyatumia ni 32 bits.

184
00:10:57,300 --> 00:11:01,850
Juu ya vifaa za kisasa zaidi kama Macs karibuni, PC karibuni, unaweza kuwa na kuyatumia 64-bit,

185
00:11:01,850 --> 00:11:04,160
lakini katika appliance, mambo haya ni ya 32 bits.

186
00:11:04,160 --> 00:11:08,380
Hivyo tutaweza standardize juu ya hilo. Zaidi concretely, hadithi inakwenda kama ifuatavyo:

187
00:11:08,380 --> 00:11:10,820
Sisi "kutangaza" pointer; gani kwamba mean?

188
00:11:10,820 --> 00:11:12,810
Sisi kuandaa kuhifadhi anwani kumbukumbu.

189
00:11:12,810 --> 00:11:15,530
Hiyo ina maana gani?

190
00:11:15,530 --> 00:11:19,810
Sisi kujenga variable inayoitwa x kwamba inachukua hadi 32 bits

191
00:11:19,810 --> 00:11:23,810
kwamba hivi karibuni kuhifadhi anwani ya integer.

192
00:11:23,810 --> 00:11:26,470
Na kwamba pengine kuhusu kama sahihi kama tunaweza kupata.

193
00:11:26,470 --> 00:11:31,810
Ni faini ya kusonga mbele kwa kurahisisha dunia na kusema tu kutangaza pointer kuitwa x.

194
00:11:31,810 --> 00:11:35,380
Kutangaza pointer, lakini kutambua na kuelewa nini hasa kinachoendelea

195
00:11:35,380 --> 00:11:38,490
hata katika wale tu wahusika wachache.

196
00:11:38,490 --> 00:11:42,040
>> Sasa, hii ni karibu rahisi kidogo, hata kama ni kujieleza tena.

197
00:11:42,040 --> 00:11:48,160
Hivyo ni nini hii kufanya, kwamba ni yalionyesha sasa: "malloc (10 * sizeof (int));" Yeah?

198
00:11:48,160 --> 00:11:52,350
[Mwanafunzi jibu, unintelligible]

199
00:11:52,350 --> 00:11:58,250
Nzuri. Na mimi itabidi kuchukua ni pale. Ni kugawa chunk ya kumbukumbu kwa integers kumi.

200
00:11:58,250 --> 00:12:02,190
Na sasa hebu kupiga mbizi katika kidogo zaidi; ni kugawa chunk ya kumbukumbu kwa integers kumi.

201
00:12:02,190 --> 00:12:05,390
Nini malloc kisha kurudi?

202
00:12:05,390 --> 00:12:10,390
anuani ya chunk kwamba, au, zaidi concretely, anuani ya Byte kwanza ya chunk kwamba.

203
00:12:10,390 --> 00:12:14,080
Jinsi ndipo ninapokuwa, programu, kujua ambapo kwamba chunk ya ncha kumbukumbu?

204
00:12:14,080 --> 00:12:18,340
Mimi najua kuwa ni contiguous. Malloc, kwa ufafanuzi, nitakupa chunk contiguous ya kumbukumbu.

205
00:12:18,340 --> 00:12:21,240
Hakuna mapengo katika hilo. Unaweza kupata kila Byte katika chunk kwamba,

206
00:12:21,240 --> 00:12:26,760
nyuma kwa nyuma kwa nyuma, lakini jinsi gani mimi kujua ambapo mwisho wa hii chunk ya kumbukumbu ni?

207
00:12:26,760 --> 00:12:28,850
Wakati matumizi malloc? [Mwanafunzi jibu, unintelligible] Good.

208
00:12:28,850 --> 00:12:30,670
Huna. Una kukumbuka.

209
00:12:30,670 --> 00:12:35,960
Mimi na kukumbuka kwamba mimi kutumika thamani 10, na mimi si hata wanaonekana wamefanya hivyo hapa.

210
00:12:35,960 --> 00:12:41,000
Lakini Wajibu ni kabisa juu yangu. Strlen, ambayo tumekuwa kuwa kidogo kujitegemea juu kwa masharti,

211
00:12:41,000 --> 00:12:45,860
kazi tu kwa sababu ya hii mkataba wa kuwa \ 0

212
00:12:45,860 --> 00:12:48,840
au hii maalum nul tabia, NUL, mwisho wa kamba.

213
00:12:48,840 --> 00:12:51,740
Kuwa haina kushikilia kwa chunks tu holela wa kumbukumbu.

214
00:12:51,740 --> 00:12:58,590
Ni juu yako. Hivyo mstari 20, basi, kutenga chunk ya kumbukumbu

215
00:12:58,590 --> 00:13:02,590
kwamba wanaweza kuhifadhi integers kumi, na huweka anuani ya Byte kwanza

216
00:13:02,590 --> 00:13:05,610
ya kwamba chunk ya kumbukumbu katika x variable kuitwa.

217
00:13:05,610 --> 00:13:11,140
Ergo, ambayo ni pointer. Hivyo mstari 21, kwa bahati mbaya, ilikuwa ni makosa.

218
00:13:11,140 --> 00:13:16,110
Lakini kwanza, ni nini ni kufanya? Ni kusema duka katika eneo 10, 0 indexed,

219
00:13:16,110 --> 00:13:19,480
ya chunk ya kumbukumbu iitwayo x 0 thamani.

220
00:13:19,480 --> 00:13:21,510
>> Hivyo taarifa michache ya mambo ni kwenda juu.

221
00:13:21,510 --> 00:13:25,420
Hata ingawa x ni pointer, wanakumbuka kutoka wiki kadhaa zilizopita

222
00:13:25,420 --> 00:13:29,440
kwamba bado unaweza kutumia safu-style mraba bracket nukuu.

223
00:13:29,440 --> 00:13:36,180
Kwa sababu hiyo ni kweli mfupi mkono nukuu kwa hesabu zaidi cryptic-kuangalia pointer.

224
00:13:36,180 --> 00:13:40,320
ambapo tunataka kufanya kitu kama hii: Chukua x anuani, hoja spots 10 juu,

225
00:13:40,320 --> 00:13:44,550
kisha kwenda huko kwa kila anuani ni kuhifadhiwa katika eneo hilo.

226
00:13:44,550 --> 00:13:48,090
Lakini kusema ukweli, hii ni mauaji ya kusoma na kupata starehe na.

227
00:13:48,090 --> 00:13:52,900
Hivyo dunia kawaida anatumia mabano mraba tu kwa sababu ni hivyo zaidi ya binadamu ya kirafiki ya kusoma.

228
00:13:52,900 --> 00:13:55,140
Lakini hiyo ni nini kweli kinachoendelea chini ya Hood;

229
00:13:55,140 --> 00:13:58,190
x ni anwani, si safu, per se.

230
00:13:58,190 --> 00:14:02,410
Hivyo hii ni hifadhi 0 katika eneo 10 katika x.

231
00:14:02,410 --> 00:14:06,120
Kwa nini hii ni mbaya? Yeah?

232
00:14:06,120 --> 00:14:17,370
[Mwanafunzi jibu, unintelligible] Hasa.

233
00:14:17,370 --> 00:14:21,100
Sisi tu zilizotengwa ints kumi, lakini sisi kuhesabu kutoka 0 wakati programu katika C,

234
00:14:21,100 --> 00:14:25,690
hivyo unaweza kupata 10 0 1 2 3 4 5 6 7 8 9, lakini si.

235
00:14:25,690 --> 00:14:30,270
Hivyo aidha mradi ni kwenda kosa seg au siyo.

236
00:14:30,270 --> 00:14:32,900
Lakini sisi si kweli kujua, hii ni aina ya tabia nondeterministic.

237
00:14:32,900 --> 00:14:35,600
Ni kweli inategemea kama sisi kupata bahati.

238
00:14:35,600 --> 00:14:40,650
Kama zinageuka kuwa mfumo wa uendeshaji haina akili kama mimi kutumia Byte ziada,

239
00:14:40,650 --> 00:14:43,360
hata ingawa haijatoa ni mimi, mpango wangu ili si ajali.

240
00:14:43,360 --> 00:14:46,780
Ni mbichi, ni Buggy, lakini unaweza kuona kuwa dalili,

241
00:14:46,780 --> 00:14:48,960
au unaweza kuona mara moja tu kwa wakati.

242
00:14:48,960 --> 00:14:51,230
Lakini ukweli ni kwamba mdudu ni, kwa kweli, kuna.

243
00:14:51,230 --> 00:14:54,320
Na ni kweli tatizo kama umefanya imeandikwa mpango kwamba unataka kuwa sahihi,

244
00:14:54,320 --> 00:14:58,840
kwamba ve kuuzwa mpango kwamba watu ni kutumia kwamba kila mara moja kwa wakati shambulio

245
00:14:58,840 --> 00:15:02,450
kwa sababu, bila shaka, hii si nzuri. Kwa kweli, kama una simu Android au iPhone

246
00:15:02,450 --> 00:15:05,550
na wewe download programu siku hizi, kama wameweza milele alikuwa App tu kujiondoa,

247
00:15:05,550 --> 00:15:10,040
ghafla ni kutoweka, hiyo ni karibu daima matokeo ya baadhi ya suala kumbukumbu-kuhusiana,

248
00:15:10,040 --> 00:15:12,830
ambapo programu Star up na dereferenced pointer

249
00:15:12,830 --> 00:15:18,670
kwamba yeye au yeye anapaswa kuwa na matokeo ya iOS au Android ni kuua tu mpango kabisa

250
00:15:18,670 --> 00:15:23,080
badala ya tabia hatarishi undefined au aina fulani ya mapatano ya usalama.

251
00:15:23,080 --> 00:15:25,950
>> Kuna moja nyingine mdudu katika mpango huu badala ya moja huu.

252
00:15:25,950 --> 00:15:30,180
Nini kingine mimi Star up katika mpango huu?

253
00:15:30,180 --> 00:15:32,740
Nimekuwa si mazoezi kile nimepata njema. Yeah?

254
00:15:32,740 --> 00:15:34,760
[Mwanafunzi jibu, unintelligible] Good.

255
00:15:34,760 --> 00:15:36,880
Mimi si huru kumbukumbu. Hivyo utawala wa kidole gumba sasa

256
00:15:36,880 --> 00:15:43,150
ina kuwa wakati wowote wewe piga malloc, lazima kuwaita bure wakati wewe ni kufanyika kwa kutumia kwamba kumbukumbu.

257
00:15:43,150 --> 00:15:45,610
Sasa, wakati nataka huru kumbukumbu hii?

258
00:15:45,610 --> 00:15:49,780
Pengine, kuchukua line hii ya kwanza ilikuwa sahihi, napenda wanataka kufanya hivyo hapa.

259
00:15:49,780 --> 00:15:55,710
Sababu sikuweza, kwa mfano, kufanya hivyo chini hapa. Kwa nini?

260
00:15:55,710 --> 00:15:57,860
Tu nje ya upeo. Hivyo hata kama sisi ni kuzungumza juu ya kuyatumia,

261
00:15:57,860 --> 00:16:04,830
hii ni wiki 2 au 3 suala hilo, ambapo x ni tu katika wigo ndani ya braces curly ambapo ilikuwa alitangaza.

262
00:16:04,830 --> 00:16:11,000
Hivyo wewe dhahiri hayawezi kumwondolea pale. Nafasi yangu tu ya bure ni takribani baada ya mstari 21.

263
00:16:11,000 --> 00:16:15,170
Hii ni programu ya haki rahisi, ilikuwa haki rahisi mara moja aina ya amefungwa akili yako

264
00:16:15,170 --> 00:16:17,870
kuzunguka kile anachokifanya mpango, ambapo makosa walikuwa.

265
00:16:17,870 --> 00:16:20,500
Na hata kama hakuwa na kuona kwa mara ya kwanza, hopefully ni kidogo dhahiri sasa

266
00:16:20,500 --> 00:16:23,870
kwamba makosa hayo ni pretty urahisi na kutatuliwa kwa urahisi kufanywa.

267
00:16:23,870 --> 00:16:28,720
Lakini wakati mpango ni zaidi ya 12 mistari ya muda mrefu, ni 50 mistari ya muda mrefu, 100 mistari ya muda mrefu,

268
00:16:28,720 --> 00:16:31,150
kutembea kwa njia ya kificho wako mstari kwa mstari, kufikiri kwa njia ya mantiki,

269
00:16:31,150 --> 00:16:35,110
inawezekana lakini si hasa fun kufanya, daima kutafuta mende,

270
00:16:35,110 --> 00:16:38,340
na pia ni vigumu kufanya hivyo, na kwamba sababu ya chombo kama Valgrind lipo.

271
00:16:38,340 --> 00:16:40,900
Hebu kwenda mbele na kufanya hili: napenda kufungua terminal yangu dirisha,

272
00:16:40,900 --> 00:16:45,400
na basi mimi si kukimbia tu kumbukumbu, kwa sababu kumbukumbu inaonekana kuwa faini.

273
00:16:45,400 --> 00:16:49,180
Nina kupata bahati. Kwenda Byte kwamba ziada mwishoni mwa safu

274
00:16:49,180 --> 00:16:51,060
haionekani kuwa pia tatizo.

275
00:16:51,060 --> 00:16:56,370
Lakini basi mimi, hata hivyo, kufanya kuangalia sanity, ambayo ina maana ya kuangalia

276
00:16:56,370 --> 00:16:58,320
kama hii ni kweli sahihi.

277
00:16:58,320 --> 00:17:04,690
>> Basi hebu kufanya valgrind-v - leak-kuangalia = kamili,

278
00:17:04,690 --> 00:17:07,520
na kisha jina la mpango katika kesi hii ni kumbukumbu, si a.out.

279
00:17:07,520 --> 00:17:10,760
Hivyo basi mimi kwenda mbele na kufanya hili. Hit Ingiza.

280
00:17:10,760 --> 00:17:14,109
Mpendwa Mungu. Hii ni pato lake, na hii ni kile alluded mapema.

281
00:17:14,109 --> 00:17:17,550
Lakini, kama wewe kujifunza kusoma kwa njia zote za nonsense hapa,

282
00:17:17,550 --> 00:17:20,760
zaidi ya hii ni uchunguzi pato kwamba si kwamba kuvutia.

283
00:17:20,760 --> 00:17:24,829
Nini jicho lako kweli anataka kuwa na kuangalia kwa ni kutaja ya makosa au batili.

284
00:17:24,829 --> 00:17:26,800
Maneno kwamba zinaonyesha matatizo.

285
00:17:26,800 --> 00:17:29,340
Na kwa kweli, hebu angalia nini kinaendelea makosa chini hapa.

286
00:17:29,340 --> 00:17:35,230
Nina muhtasari wa aina fulani, "katika matumizi ya exit. 40 ka katika vitalu 1"

287
00:17:35,230 --> 00:17:38,750
Mimi nina uhakika nini kuzuia ni bado, lakini 40 bytes

288
00:17:38,750 --> 00:17:41,260
kweli anahisi kama mimi naweza kufikiri ambapo ule unaokuja kutoka.

289
00:17:41,260 --> 00:17:45,030
40 bytes. Kwa nini ni ka 40 katika matumizi ya exit?

290
00:17:45,030 --> 00:17:48,780
Na hasa zaidi, kama sisi kitabu chini hapa,

291
00:17:48,780 --> 00:17:54,520
mbona mimi dhahiri waliopotea ka 40? Yeah?

292
00:17:54,520 --> 00:17:59,520
[Mwanafunzi jibu, unintelligible] Perfect. Yeah, kwa uhakika.

293
00:17:59,520 --> 00:18:03,540
Kulikuwa kumi integers, na kila mmoja wa wale ni ukubwa wa bits 4, au 32,

294
00:18:03,540 --> 00:18:08,300
hivyo nimekuwa waliopotea ka just 40 kwa sababu, kama wewe mapendekezo, mimi si kuitwa bure.

295
00:18:08,300 --> 00:18:13,460
Hiyo ni moja mdudu, na sasa hebu angalia chini kidogo zaidi na kuona ijayo na hii,

296
00:18:13,460 --> 00:18:16,900
"Batili kuandika ukubwa wa 4." Sasa ni nini hii?

297
00:18:16,900 --> 00:18:21,150
Anuani hii ni walionyesha nini msingi nukuu, inaonekana?

298
00:18:21,150 --> 00:18:23,640
Hii ni hexadesimoli, na wakati wowote unaweza kuona idadi kuanzia na 0x,

299
00:18:23,640 --> 00:18:29,410
maana hexadesimoli, ambayo sisi alifanya njia ya nyuma katika, nadhani, pset 0 wa sehemu ya maswali,

300
00:18:29,410 --> 00:18:34,090
ambayo ilikuwa tu kufanya zoezi warmup, kuwabadili decimal kwa hex kwa binary na kadhalika.

301
00:18:34,090 --> 00:18:39,220
Hexadesimoli, tu kwa mkataba wa binadamu, ni kawaida kutumika kuwakilisha kuyatumia

302
00:18:39,220 --> 00:18:41,570
au, kwa ujumla zaidi, anwani. Ni tu mkataba,

303
00:18:41,570 --> 00:18:45,340
kwa sababu ni rahisi kidogo kusoma, ni zaidi kidogo kuliko Compact kitu kama decimal,

304
00:18:45,340 --> 00:18:47,720
na kisha ni bure kwa ajili ya wengi binadamu kutumia.

305
00:18:47,720 --> 00:18:50,840
Hivyo sasa nini maana ya hii? Naam, inaonekana kama kuna kuandika batili

306
00:18:50,840 --> 00:18:54,480
ya ukubwa 4 kwenye mstari 21 ya memory.c.

307
00:18:54,480 --> 00:18:59,180
Basi hebu kwenda nyuma ya mstari 21, na kwa kweli, hapa ni kwamba kuandika batili.

308
00:18:59,180 --> 00:19:02,640
Hivyo Valgrind si kwenda kabisa kushikilia mkono wangu na kuniambia nini fix ni,

309
00:19:02,640 --> 00:19:05,520
lakini ni kuchunguza kwamba mimi nina kufanya kuandika batili.

310
00:19:05,520 --> 00:19:08,800
Mimi kugusa ka 4 kwamba nisiwe, na inaonekana kwamba kwa sababu,

311
00:19:08,800 --> 00:19:13,960
kama wewe alisema, mimi nina kufanya [10] badala ya [9] Upeo

312
00:19:13,960 --> 00:19:16,660
au [0] au kitu katika kati.

313
00:19:16,660 --> 00:19:19,690
Kwa Valgrind, kutambua wakati wowote wewe ni sasa kuandika mpango

314
00:19:19,690 --> 00:19:24,190
kwamba anatumia kuyatumia na anatumia kumbukumbu, na malloc zaidi hasa,

315
00:19:24,190 --> 00:19:27,080
dhahiri kupata katika tabia ya kuendesha kwa muda mrefu

316
00:19:27,080 --> 00:19:30,890
lakini kwa urahisi sana kunakiliwa na pasted amri ya Valgrind

317
00:19:30,890 --> 00:19:32,650
kuona kama kuna baadhi ya makosa katika huko.

318
00:19:32,650 --> 00:19:34,820
Na utakuwa ni balaa kila wakati unaweza kuona pato,

319
00:19:34,820 --> 00:19:39,430
lakini tu Hazrat kupitia kuibua wote wa pato na kuona kama unaweza kuona inataja wa makosa

320
00:19:39,430 --> 00:19:43,190
au maonyo au batili au kupotea.

321
00:19:43,190 --> 00:19:46,200
Yoyote maneno kwamba sauti kama wewe Star up mahali fulani.

322
00:19:46,200 --> 00:19:48,580
Hivyo kutambua kwamba ni chombo kipya katika toolkit yako.

323
00:19:48,580 --> 00:19:51,270
>> Sasa siku ya Jumatatu, tulikuwa na rundo zima la folks kuja hapa

324
00:19:51,270 --> 00:19:53,150
na kuwakilisha dhana ya orodha zinazoungwa.

325
00:19:53,150 --> 00:20:00,970
Na sisi ilianzisha orodha wanaohusishwa kama ufumbuzi wa tatizo nini?

326
00:20:00,970 --> 00:20:04,590
Yeah? [Mwanafunzi jibu, unintelligible] Good.

327
00:20:04,590 --> 00:20:06,530
Arrays hawezi kuwa na kumbukumbu aliongeza kwao.

328
00:20:06,530 --> 00:20:09,440
Kama wewe kutenga safu ya kawaida 10, kwamba ni yote wewe kupata.

329
00:20:09,440 --> 00:20:13,690
Unaweza kuita kazi kama realloc kama awali kuitwa malloc,

330
00:20:13,690 --> 00:20:17,580
na kwamba unaweza kujaribu kukua safu kama kuna nafasi kuelekea mwisho wa

331
00:20:17,580 --> 00:20:21,610
kwamba hakuna mtu mwingine ni kutumia, na kama kuna si, itakuwa tu kupata wewe chunk kubwa mahali pengine.

332
00:20:21,610 --> 00:20:25,040
Lakini basi itakuwa nakala yote ya ka wale katika safu mpya.

333
00:20:25,040 --> 00:20:28,310
Hii inaonekana kama ufumbuzi sahihi kabisa.

334
00:20:28,310 --> 00:20:34,790
Kwa nini hii ni unattractive?

335
00:20:34,790 --> 00:20:36,940
I mean ni kazi, binadamu kuwa wametatua tatizo hili.

336
00:20:36,940 --> 00:20:40,710
Kwa nini tunahitaji kutatua Jumatatu na orodha wanaohusishwa? Yeah?

337
00:20:40,710 --> 00:20:44,060
[Mwanafunzi jibu, unintelligible] Ni inaweza kuchukua muda mrefu.

338
00:20:44,060 --> 00:20:49,260
Kwa kweli, wakati wowote wewe ni wito malloc au realloc au calloc, ambayo bado mwingine mmoja,

339
00:20:49,260 --> 00:20:52,470
wakati wowote, mpango, ni kuzungumza na mfumo wa uendeshaji,

340
00:20:52,470 --> 00:20:54,310
wewe huwa na kupunguza mpango chini.

341
00:20:54,310 --> 00:20:57,470
Na kama wewe ni kufanya aina hii ya mambo katika tanzi, wewe ni kweli kupunguza mambo chini.

342
00:20:57,470 --> 00:21:00,740
Wewe hutaenda kwa taarifa hii kwa rahisi ya "hello dunia" programu aina,

343
00:21:00,740 --> 00:21:04,300
lakini katika mipango kubwa sana, kuuliza mfumo wa uendeshaji tena na tena kwa kumbukumbu

344
00:21:04,300 --> 00:21:07,520
au kutoa ni nyuma tena na tena huelekea si kwa kuwa ni jambo jema.

345
00:21:07,520 --> 00:21:11,210
Plus, ni tu aina ya kielimu - ni kupoteza kamili ya muda.

346
00:21:11,210 --> 00:21:16,490
Mbona kutenga zaidi na zaidi ya kumbukumbu, hatari kuiga kila kitu ndani ya safu mpya,

347
00:21:16,490 --> 00:21:21,980
kama una mbadala ambayo inakuwezesha kutenga tu kama kumbukumbu kubwa zaidi kama wewe kweli wanahitaji?

348
00:21:21,980 --> 00:21:24,130
Hivyo kuna pluses na minuses katika hapa.

349
00:21:24,130 --> 00:21:26,730
Moja ya pluses sasa ni kwamba tuna mabadiliko.

350
00:21:26,730 --> 00:21:29,100
Haijalishi ambapo chunks ya kumbukumbu ni kwamba ni bure,

351
00:21:29,100 --> 00:21:32,070
Naweza tu ya aina ya kujenga makombo haya mkate kupitia kuyatumia

352
00:21:32,070 --> 00:21:34,470
kwa kamba wanaohusishwa wangu wote orodha pamoja.

353
00:21:34,470 --> 00:21:36,470
Lakini mimi kulipa angalau moja ya bei.

354
00:21:36,470 --> 00:21:40,060
>> Nifanye uwachane katika kupata orodha wanaohusishwa?

355
00:21:40,060 --> 00:21:42,470
Yeah? [Mwanafunzi jibu, unintelligible] Good.

356
00:21:42,470 --> 00:21:45,650
Unahitaji kumbukumbu zaidi. Sasa mimi wanahitaji nafasi kwa kuyatumia haya,

357
00:21:45,650 --> 00:21:47,900
na katika kesi ya orodha hii super rahisi wanaohusishwa

358
00:21:47,900 --> 00:21:51,410
kwamba ni tu kujaribu kuhifadhi integers, ambayo ni 4 ka, sisi kuendelea kusema

359
00:21:51,410 --> 00:21:54,240
vizuri, pointer ni 4 ka, hivyo sasa nimepata literally mara mbili

360
00:21:54,240 --> 00:21:57,290
kiasi cha kumbukumbu nahitaji tu kuhifadhi orodha hii.

361
00:21:57,290 --> 00:21:59,680
Lakini tena, hii ni mara kwa mara katika tradeoff sayansi ya kompyuta

362
00:21:59,680 --> 00:22:03,440
kati ya muda na nafasi na maendeleo, juhudi na rasilimali nyingine.

363
00:22:03,440 --> 00:22:06,630
Nini mwingine upande wa chini ya kutumia orodha wanaohusishwa? Yeah?

364
00:22:06,630 --> 00:22:10,150
[Mwanafunzi jibu, unintelligible]

365
00:22:10,150 --> 00:22:12,600
Nzuri. Kama si rahisi kupata. Tunaweza tena kujiinua

366
00:22:12,600 --> 00:22:15,530
wiki kanuni 0 kama kugawanya na kushinda.

367
00:22:15,530 --> 00:22:18,220
Na hasa zaidi, binary tafuta. Kwa sababu hata kama sisi binadamu

368
00:22:18,220 --> 00:22:20,400
unaweza kuona takribani ambapo katikati ya orodha hii ni,

369
00:22:20,400 --> 00:22:25,840
kompyuta tu anajua kwamba hii orodha wanaohusishwa kuanza saa anuani kuitwa kwanza.

370
00:22:25,840 --> 00:22:28,250
Na kwamba 0x123 au kitu kama hicho.

371
00:22:28,250 --> 00:22:30,990
Na njia pekee ya mpango unaweza kupata kipengele katikati

372
00:22:30,990 --> 00:22:33,350
ni kweli kutafuta orodha nzima.

373
00:22:33,350 --> 00:22:35,500
Na hata basi, ni literally inapaswa kutafuta orodha nzima kwa sababu

374
00:22:35,500 --> 00:22:38,950
hata mara moja wewe kufikia katikati ya kipengele kwa kufuata kuyatumia,

375
00:22:38,950 --> 00:22:42,380
wewe, mpango, hawana wazo jinsi ya muda mrefu orodha hii ni, uwezekano,

376
00:22:42,380 --> 00:22:45,250
mpaka hit mwisho wake, na jinsi gani unajua programmatically

377
00:22:45,250 --> 00:22:48,600
kwamba uko katika mwisho wa orodha wanaohusishwa?

378
00:22:48,600 --> 00:22:51,120
Kuna maalum null pointer, hivyo tena, mkataba.

379
00:22:51,120 --> 00:22:53,870
Badala ya kutumia hii pointer, sisi dhahiri hawataki kuwa ni baadhi ya thamani ya takataka

380
00:22:53,870 --> 00:22:57,750
akizungumzia hatua mbali mahali fulani; sisi nataka kuwa mkono chini, null,

381
00:22:57,750 --> 00:23:01,530
hivyo kwamba tuna hii terminus katika muundo huu data hivyo tunajua ambapo ni mwisho.

382
00:23:01,530 --> 00:23:03,410
>> Nini kama tunataka kuendesha hii?

383
00:23:03,410 --> 00:23:05,980
Sisi gani zaidi ya huu kuibua, na kwa binadamu,

384
00:23:05,980 --> 00:23:07,630
lakini nini kama tunataka kufanya insertion?

385
00:23:07,630 --> 00:23:12,360
Hivyo orodha ya awali ilikuwa 9, 17, 20, 22, 29, 34.

386
00:23:12,360 --> 00:23:16,730
Nini kama sisi basi alitaka nafasi malloc kwa idadi 55, nodi kwa ajili yake,

387
00:23:16,730 --> 00:23:20,730
na kisha tunataka Insert 55 katika orodha tu kama tulivyofanya Jumatatu?

388
00:23:20,730 --> 00:23:23,690
Tutafanyaje hili? Naam, Anita alikuja na yeye kimsingi kutembea orodha.

389
00:23:23,690 --> 00:23:27,500
Alianza katika kipengele kwanza, kisha ya pili, pili, pili, pili, pili.

390
00:23:27,500 --> 00:23:29,500
Hatimaye hit mkono wa kushoto njia yote chini

391
00:23:29,500 --> 00:23:34,480
na barabara oh, hii ni null. Basi nini pointer ghiliba zinahitajika kufanyika?

392
00:23:34,480 --> 00:23:37,980
mtu ambaye alikuwa juu ya mwisho, idadi 34, zinahitajika mkono wake wa kushoto alimfufua

393
00:23:37,980 --> 00:23:46,220
kwa uhakika ya 55, 55 zinahitajika mkono wao wa kushoto akizungumzia chini kuwa mpya null Terminator. Done.

394
00:23:46,220 --> 00:23:49,540
Pretty rahisi Insert 55 katika orodha Iliyopangwa.

395
00:23:49,540 --> 00:23:51,800
Na jinsi inaweza hii kuangalia?

396
00:23:51,800 --> 00:23:55,690
>> Hebu kwenda mbele na kufungua baadhi mfano code hapa.

397
00:23:55,690 --> 00:23:58,120
Mimi itabidi kufungua gedit, na napenda kufungua files mbili kwanza.

398
00:23:58,120 --> 00:24:02,050
Moja ni list1.h, na napenda tu kuwakumbusha kwamba hii ilikuwa chunk ya maadili ya

399
00:24:02,050 --> 00:24:04,920
kwamba sisi kutumika kuwakilisha nodi.

400
00:24:04,920 --> 00:24:13,040
nodi ina wawili int kuitwa n na pointer iitwayo ijayo kwamba tu pointi kwa Kilichofuata katika orodha.

401
00:24:13,040 --> 00:24:15,450
Hiyo ni sasa katika faili h.. Kwa nini?

402
00:24:15,450 --> 00:24:19,090
Kuna mkataba huu, na sisi si kuchukuliwa kwa faida ya kiasi hiki kikubwa wenyewe,

403
00:24:19,090 --> 00:24:22,220
lakini mtu ambaye aliandika kazi printf na nyingine

404
00:24:22,220 --> 00:24:27,150
alitoa kama zawadi kwa ulimwengu wote wa kazi hizo kwa kuandika faili inayoitwa stdio.h.

405
00:24:27,150 --> 00:24:30,950
Na kisha kuna string.h, na kisha kuna map.h, na kuna files haya yote h

406
00:24:30,950 --> 00:24:34,410
kwamba unaweza kuwa na kuonekana au kutumika wakati wa muda imeandikwa na watu wengine.

407
00:24:34,410 --> 00:24:38,470
Kawaida katika wale h files. Ni mambo tu kama typedefs

408
00:24:38,470 --> 00:24:42,310
au maazimio ya aina desturi au maazimio ya constants.

409
00:24:42,310 --> 00:24:47,890
Huwezi kuweka utekelezaji kazi 'katika files header.

410
00:24:47,890 --> 00:24:50,570
Kuweka, badala yake, prototypes tu wao.

411
00:24:50,570 --> 00:24:53,050
Wewe kuweka mambo unataka kushiriki na duniani wanahitaji nini

412
00:24:53,050 --> 00:24:55,640
ili kukusanya kanuni zao. Hivyo tu kwa kuingia katika tabia hii,

413
00:24:55,640 --> 00:24:59,110
tuliamua kufanya kitu kimoja. Kuna si sana katika list1.h,

414
00:24:59,110 --> 00:25:02,070
lakini tumekuwa kuweka kitu ambayo inaweza kuwa ya manufaa kwa watu katika ulimwengu

415
00:25:02,070 --> 00:25:05,030
ambao wanataka kutumia orodha yetu zilizounganishwa utekelezaji.

416
00:25:05,030 --> 00:25:08,040
Sasa, katika list1.c, mimi si kwenda kwa jambo hili zima

417
00:25:08,040 --> 00:25:11,390
kwa sababu ni kidogo kwa muda mrefu, programu hii, lakini hebu kukimbia kweli haraka katika haraka.

418
00:25:11,390 --> 00:25:15,720
Hebu kukusanya list1, napenda kisha kukimbia list1, na kile utaona ni

419
00:25:15,720 --> 00:25:18,070
tumekuwa simulated rahisi kidogo mpango hapa

420
00:25:18,070 --> 00:25:20,990
ambayo inaenda naomba kuongeza na kuondoa idadi ya orodha.

421
00:25:20,990 --> 00:25:24,310
Hivyo basi mimi kwenda mbele na aina 3 kwa 3 chaguo menu.

422
00:25:24,310 --> 00:25:27,880
Mimi nataka kuingiza idadi - wacha kufanya idadi ya kwanza, ambayo ilikuwa 9,

423
00:25:27,880 --> 00:25:30,550
na sasa mimi nina aliiambia orodha ni sasa 9.

424
00:25:30,550 --> 00:25:33,760
Hebu kwenda mbele na kufanya mwingine insertion, hivyo mimi hit menu chaguo 3.

425
00:25:33,760 --> 00:25:36,760
Nini idadi mimi nataka Insert? 17.

426
00:25:36,760 --> 00:25:39,220
Kuingia. Na mimi itabidi kufanya moja tu zaidi.

427
00:25:39,220 --> 00:25:41,720
Hebu Insert namba 22.

428
00:25:41,720 --> 00:25:45,850
Hivyo tuna mwanzo wa orodha wanaohusishwa kwamba tulikuwa katika fomu slide wakati iliyopita.

429
00:25:45,850 --> 00:25:48,740
Jinsi ni insertion hii kwa kweli yanatokea?

430
00:25:48,740 --> 00:25:52,000
Hakika, 22 ni sasa mwisho wa orodha.

431
00:25:52,000 --> 00:25:55,050
Hivyo hadithi tunaambiwa juu ya hatua ya juu ya Jumatatu na recapped tu sasa

432
00:25:55,050 --> 00:25:57,460
lazima kweli kuwa kinachotokea katika code.

433
00:25:57,460 --> 00:25:59,700
Hebu tuangalie. Hebu kitabu chini katika faili hii.

434
00:25:59,700 --> 00:26:01,720
Tutaweza Gloss juu ya baadhi ya kazi,

435
00:26:01,720 --> 00:26:05,630
lakini tutaweza kwenda chini, wanasema, kazi Insert.

436
00:26:05,630 --> 00:26:11,720
>> Hebu angalia jinsi sisi kwenda juu ya inserting nodi mpya katika orodha hii zinazoungwa.

437
00:26:11,720 --> 00:26:14,550
Ambapo ni orodha alitangaza? Naam, hebu kitabu njia yote hadi saa ya juu,

438
00:26:14,550 --> 00:26:19,970
na taarifa kwamba orodha yangu wanaohusishwa ni kimsingi alitangaza kama pointer moja kwamba awali null.

439
00:26:19,970 --> 00:26:23,180
Basi, mimi nina kutumia variable kimataifa hapa, ambayo kwa ujumla tumekuwa alihubiri dhidi ya

440
00:26:23,180 --> 00:26:25,280
kwa sababu inafanya code yako messy kidogo ili kudumisha,

441
00:26:25,280 --> 00:26:29,080
ni aina ya wavivu, kwa kawaida, lakini si wavivu na si vibaya na si mbaya

442
00:26:29,080 --> 00:26:33,660
kama mpango wako lengo pekee katika maisha ni kuiga moja zilizounganishwa orodha.

443
00:26:33,660 --> 00:26:35,460
Ambayo ni sawa kabisa sisi ni kufanya.

444
00:26:35,460 --> 00:26:39,100
Hivyo badala ya kutangaza hii katika kuu na kisha kuwa na kupita kwa kila kazi

445
00:26:39,100 --> 00:26:42,640
tumekuwa yaliyoandikwa katika mpango huu, sisi badala kutambua oh, hebu tu kufanya hivyo kimataifa

446
00:26:42,640 --> 00:26:47,060
sababu lengo zima la mpango huu ni kuonyesha moja na moja tu wanaohusishwa orodha.

447
00:26:47,060 --> 00:26:50,700
Hivyo kwamba anahisi sawa. Hapa ni prototypes wangu, na sisi si kwenda kwa yote haya,

448
00:26:50,700 --> 00:26:55,800
lakini mimi aliandika kazi ya kufuta, kazi kupata, kazi Insert, na kazi tindanga.

449
00:26:55,800 --> 00:26:59,080
Lakini hebu sasa kwenda nyuma chini na kazi Insert

450
00:26:59,080 --> 00:27:01,490
na kuona jinsi hii moja kazi hapa.

451
00:27:01,490 --> 00:27:09,940
Insert ni juu ya mstari - hapa sisi kwenda.

452
00:27:09,940 --> 00:27:12,850
Ingiza. Hivyo haina kuchukua hoja yoyote, kwa sababu sisi ni kwenda kuuliza

453
00:27:12,850 --> 00:27:15,930
ndani ya mtumiaji wa kazi hii kwa idadi wanataka Insert.

454
00:27:15,930 --> 00:27:19,410
Lakini kwanza, sisi kujiandaa ili kuwapa baadhi ya nafasi.

455
00:27:19,410 --> 00:27:22,050
Hii ni aina ya nakala na kuweka mfano kutoka nyingine.

456
00:27:22,050 --> 00:27:25,110
Katika kesi hiyo, tulikuwa kugawa int; wakati huu tuko kugawa nodi.

457
00:27:25,110 --> 00:27:27,910
Mimi si kweli kumbuka jinsi wengi ka nodi ni, lakini hiyo ni nzuri.

458
00:27:27,910 --> 00:27:30,460
Sizeof wanaweza kufikiri kuwa nje kwa ajili yangu.

459
00:27:30,460 --> 00:27:33,340
Na kwa nini mimi kuangalia kwa null katika mstari 120?

460
00:27:33,340 --> 00:27:37,530
Je, inaweza kwenda vibaya katika mstari 119? Yeah?

461
00:27:37,530 --> 00:27:40,530
[Mwanafunzi jibu, unintelligible]

462
00:27:40,530 --> 00:27:43,440
Nzuri. Tu inaweza kuwa kesi kwamba nimepata aliuliza kwa kumbukumbu sana

463
00:27:43,440 --> 00:27:47,020
au kitu vibaya na mfumo wa uendeshaji haina ka kutosha kutoa yangu,

464
00:27:47,020 --> 00:27:50,640
hivyo ni ishara sana kwa kurudi null, na kama si kuangalia kwa kuwa

465
00:27:50,640 --> 00:27:54,710
na mimi tu upofu kuendelea kutumia anuani wakarudi, inaweza kuwa null.

466
00:27:54,710 --> 00:27:58,400
Ni inaweza kuwa baadhi ya thamani haijulikani; si jambo zuri isipokuwa mimi -

467
00:27:58,400 --> 00:28:00,590
kweli si kuwa thamani haijulikani. Ni inaweza kuwa null, hivyo sitaki

468
00:28:00,590 --> 00:28:02,550
dhuluma hiyo na kuhatarisha dereferencing yake.

469
00:28:02,550 --> 00:28:07,410
Kama kwamba hutokea, mimi tu kurudi na tutaweza kujifanya kama sikuweza kupata nyuma yoyote kumbukumbu wakati wote.

470
00:28:07,410 --> 00:28:12,270
>> Vinginevyo, mimi kuwaambia mtumiaji nipe namba Insert, mimi kuwaita rafiki yetu ya zamani GetInt,

471
00:28:12,270 --> 00:28:15,530
na kisha hii ilikuwa syntax mpya sisi ilianzisha Jumatatu.

472
00:28:15,530 --> 00:28:20,320
'Newptr-> n' ina maana kuchukua anuani kwamba walipewa kwa malloc

473
00:28:20,320 --> 00:28:23,490
ambayo inawakilisha Byte kwanza ya kitu mpya wa nodi,

474
00:28:23,490 --> 00:28:26,860
na kisha kwenda shamba iitwayo n.

475
00:28:26,860 --> 00:28:35,270
kidogo trivia swali: Hii ni sawa na mstari nini zaidi cryptic ya maadili?

476
00:28:35,270 --> 00:28:38,110
Jinsi mwingine inaweza nimeandika hii? Wanataka kuchukua kumchoma?

477
00:28:38,110 --> 00:28:41,480
[Mwanafunzi jibu, unintelligible]

478
00:28:41,480 --> 00:28:44,870
Nzuri. Kutumia n., Lakini siyo kabisa kama rahisi kama hii.

479
00:28:44,870 --> 00:28:47,090
Nifanye kwanza haja ya kufanya? [Mwanafunzi jibu, unintelligible]

480
00:28:47,090 --> 00:28:52,730
Nzuri. Mimi haja ya kufanya * newptr.n.

481
00:28:52,730 --> 00:28:55,610
Hivyo hii ni kusema pointer mpya ni wazi anuani. Kwa nini?

482
00:28:55,610 --> 00:28:59,520
Sababu ilikuwa akarudi na malloc. Newptr * akisema "kwenda huko,"

483
00:28:59,520 --> 00:29:02,970
na kisha mara moja uko pale, basi unaweza kutumia zaidi ya ukoo n.,

484
00:29:02,970 --> 00:29:05,730
lakini hii tu inaonekana kidogo ugly, hasa kama sisi binadamu ni kwenda

485
00:29:05,730 --> 00:29:10,360
kuteka kuyatumia kwa mishale wakati wote; dunia ina sanifu kwenye nukuu hii mshale,

486
00:29:10,360 --> 00:29:12,320
ambayo haina hasa kitu kimoja.

487
00:29:12,320 --> 00:29:16,070
Hivyo matumizi tu -> nukuu wakati kitu upande wa kushoto ni pointer.

488
00:29:16,070 --> 00:29:18,790
Vinginevyo, kama ni struct halisi, matumizi n..

489
00:29:18,790 --> 00:29:25,800
Na kisha hii: Kwa nini mimi initialize newptr-> ijayo null?

490
00:29:25,800 --> 00:29:28,610
Hatutaki dangling kushoto mbali ya mwisho ya hatua.

491
00:29:28,610 --> 00:29:31,630
Tunataka hiyo unaelekea chini, ambayo ina maana ya mwisho wa orodha hii

492
00:29:31,630 --> 00:29:34,980
inaweza uwezekano wa kuwa kwenye nodi hii, hivyo sisi ni bora kuhakikisha kuwa ni null.

493
00:29:34,980 --> 00:29:38,460
Na, kwa ujumla, initializing vigezo au data yako wanachama na structs

494
00:29:38,460 --> 00:29:40,470
kwa kitu ni mazoezi mazuri.

495
00:29:40,470 --> 00:29:45,170
Just kuruhusu takataka kuwepo na kuendelea kuwepo kwa ujumla anapata shida katika

496
00:29:45,170 --> 00:29:48,650
kama wewe kusahau kufanya kitu baadaye.

497
00:29:48,650 --> 00:29:51,590
>> Hapa ni kesi chache. Hii, tena, ni kazi Insert,

498
00:29:51,590 --> 00:29:54,930
na jambo la kwanza mimi kuangalia kwa ni kama variable iitwayo ya kwanza,

499
00:29:54,930 --> 00:29:58,240
kwamba variable kimataifa ni null, kwamba maana hakuna orodha zinazoungwa.

500
00:29:58,240 --> 00:30:02,460
Sisi si kuingizwa idadi yoyote, hivyo ni trivial kuingiza idadi hii ya sasa

501
00:30:02,460 --> 00:30:05,240
katika orodha, kwa sababu tu ni wakati wa kuanza kwa orodha.

502
00:30:05,240 --> 00:30:08,100
Hivyo hii ilikuwa wakati Anita mara tu alisimama hapa peke yake, akijifanya

503
00:30:08,100 --> 00:30:11,390
hakuna mtu mwingine alikuwa hapa juu ya hatua mpaka sisi zilizotengwa nodi,

504
00:30:11,390 --> 00:30:13,940
kisha aliweza kunyanyua mkono wake kwa mara ya kwanza,

505
00:30:13,940 --> 00:30:17,420
kama kila mtu mwingine waliokuja juu ya hatua baada yake juu ya Jumatatu.

506
00:30:17,420 --> 00:30:22,900
Sasa hapa, hii ni hundi kidogo ambapo mimi kusema kama thamani ya nodi ya mwezi wa n

507
00:30:22,900 --> 00:30:27,370
ni <thamani ya n katika nodi ya sasa ya kwanza,

508
00:30:27,370 --> 00:30:29,930
hiyo ina maana kuna orodha zilizounganishwa kwamba imeanza.

509
00:30:29,930 --> 00:30:32,330
Kuna angalau moja nodi katika orodha, lakini guy hii mpya

510
00:30:32,330 --> 00:30:37,230
ni kabla ya hivyo, hivyo tunahitaji kusonga mambo kote.

511
00:30:37,230 --> 00:30:43,450
Kwa maneno mengine, kama orodha imeanza na tu, hebu sema,

512
00:30:43,450 --> 00:30:48,100
idadi tu ya 17, kwamba ni - kwa kweli, tunaweza kufanya hili wazi zaidi.

513
00:30:48,100 --> 00:30:56,010
Kama sisi kuanza hadithi wetu na pointer hapa iitwayo ya kwanza,

514
00:30:56,010 --> 00:30:59,870
na mwanzoni ni null, na sisi Insert namba 9,

515
00:30:59,870 --> 00:31:02,510
namba 9 wazi ni mwanzo wa orodha.

516
00:31:02,510 --> 00:31:07,400
Basi hebu kujifanya sisi tu malloced anuani au namba 9 na kuiweka hapa.

517
00:31:07,400 --> 00:31:13,170
Kama ni ya kwanza 9 by default, tukio la kwanza sisi kujadiliwa tu ina maana uhakika hebu guy hii hapa,

518
00:31:13,170 --> 00:31:15,790
kuacha hii kama null; sasa tuna idadi 9.

519
00:31:15,790 --> 00:31:18,280
idadi ijayo tunataka Insert ni 17.

520
00:31:18,280 --> 00:31:22,420
17 ni zaidi ya hapa, hivyo sisi ni kwenda kufanya baadhi wanazidi mantiki kwa njia hii.

521
00:31:22,420 --> 00:31:26,060
Basi hebu badala yake, kabla ya sisi kufanya hivyo, hebu kujifanya kuwa tulitaka kuingiza namba 8.

522
00:31:26,060 --> 00:31:28,650
>> Hivyo tu kwa ajili ya urahisi, mimi nina kwenda kuteka hapa.

523
00:31:28,650 --> 00:31:30,760
Lakini kumbuka, malloc waiweke wengi mahali popote.

524
00:31:30,760 --> 00:31:33,460
Lakini kwa ajili ya kuchora, mimi itabidi kuweka hapa.

525
00:31:33,460 --> 00:31:38,440
Hivyo kujifanya nimekuwa tu zilizotengwa kwa ajili ya nodi namba 8, hii ni kwa default null.

526
00:31:38,440 --> 00:31:42,800
Nini sasa ina kutokea? michache ya mambo.

527
00:31:42,800 --> 00:31:47,090
Sisi alifanya hii kosa juu ya hatua ya Jumatatu ambapo sisi updated pointer kama hii,

528
00:31:47,090 --> 00:31:51,890
kisha alifanya hivyo, na kisha sisi alidai - sisi yatima kila mtu mwingine juu ya hatua.

529
00:31:51,890 --> 00:31:54,350
Kwa sababu wewe can't - utaratibu wa shughuli hapa ni muhimu,

530
00:31:54,350 --> 00:31:58,760
kwa sababu sasa tumekuwa wamepoteza 9 nodi kwamba ni aina ya yaliyo katika nafasi.

531
00:31:58,760 --> 00:32:01,150
Hivyo hii si njia ya haki juu ya Jumatatu.

532
00:32:01,150 --> 00:32:03,330
Sisi kwanza kufanya kitu kingine.

533
00:32:03,330 --> 00:32:06,280
hali ya dunia inaonekana kama hii. Awali, 8 imetengewa.

534
00:32:06,280 --> 00:32:10,550
Nini itakuwa njia bora ya inserting 8?

535
00:32:10,550 --> 00:32:14,720
Badala ya uppdatering hii pointer kwanza, tu update hii moja hapa badala yake.

536
00:32:14,720 --> 00:32:17,720
Hivyo tunahitaji mstari wa kanuni ambayo inaenda kugeuka tabia hii null

537
00:32:17,720 --> 00:32:22,020
ndani ya pointer halisi hiyo akionyesha nodi 9,

538
00:32:22,020 --> 00:32:27,970
na kisha tunaweza kwa usalama mabadiliko kwanza kwa uhakika katika guy hii hapa.

539
00:32:27,970 --> 00:32:31,330
Sasa tuna orodha, orodha wanaohusishwa, vipengele viwili.

540
00:32:31,330 --> 00:32:33,580
Na nini hii kwa kweli kuangalia kama hapa?

541
00:32:33,580 --> 00:32:36,900
Kama sisi kuangalia code, taarifa kwamba mimi tumefanya hasa ile.

542
00:32:36,900 --> 00:32:41,970
Nilivyosema newptr, na katika hadithi hii, newptr alikuwa akionyesha guy.

543
00:32:41,970 --> 00:32:45,520
>> Hivyo basi mimi kuteka jambo moja zaidi, na mimi wanapaswa kushoto kidogo zaidi ya chumba kwa ajili hii.

544
00:32:45,520 --> 00:32:48,540
Unisamehe kidogo kidogo kuchora.

545
00:32:48,540 --> 00:32:52,140
Guy Hii inaitwa newptr.

546
00:32:52,140 --> 00:32:57,940
Hiyo ni variable sisi alitangaza mistari michache kabla ya hapo, katika line - tu juu ya 25.

547
00:32:57,940 --> 00:33:03,430
Na ni akizungumzia 8. Hivyo wakati mimi kusema newptr-> ijayo, kwamba maana ya kwenda struct

548
00:33:03,430 --> 00:33:07,910
kwamba ni kuwa alisema katika na newptr, hivyo hapa sisi ni, kwenda huko.

549
00:33:07,910 --> 00:33:13,990
Kisha mshale ni kusema kupata shamba ijayo, na kisha = ni kusema kuweka thamani gani huko?

550
00:33:13,990 --> 00:33:17,280
thamani hiyo ilikuwa katika kwanza; thamani gani ilikuwa katika kwanza?

551
00:33:17,280 --> 00:33:21,930
Kwanza alikuwa akizungumzia nodi katika hili, hivyo kwamba maana hii lazima sasa kumweka kwenye nodi hii.

552
00:33:21,930 --> 00:33:25,660
Kwa maneno mengine, kile inaonekana angalau fujo ridiculous kwa mwandiko wangu,

553
00:33:25,660 --> 00:33:28,620
nini wazo rahisi ya kusonga tu mishale hizi karibu

554
00:33:28,620 --> 00:33:31,560
tafsiri ya kificho na mjengo tu hii moja.

555
00:33:31,560 --> 00:33:38,110
Hifadhi ni nini katika kwanza katika uwanja ijayo na kisha update nini kwanza kweli ni.

556
00:33:38,110 --> 00:33:40,900
Hebu kwenda mbele na kufunga-mbele kupitia baadhi ya hii,

557
00:33:40,900 --> 00:33:44,220
na kuangalia tu katika insertion hii mkia kwa sasa.

558
00:33:44,220 --> 00:33:51,210
Tuseme mimi kupata kwa uhakika ambapo mimi kupata kwamba shamba ya pili ya nodi baadhi ni null.

559
00:33:51,210 --> 00:33:53,410
Na katika hatua hii ya hadithi, undani kwamba mimi nina glossing juu ya

560
00:33:53,410 --> 00:33:58,170
ni kwamba nimepata ilianzisha mwingine pointer hapa juu katika mstari 142, mtangulizi pointer.

561
00:33:58,170 --> 00:34:01,320
Kimsingi, katika hatua hii ya hadithi, mara moja orodha anapata muda mrefu,

562
00:34:01,320 --> 00:34:04,800
Mimi aina ya haja ya kutembea kwa vidole viwili kwa sababu kama mimi kwenda mbali mno,

563
00:34:04,800 --> 00:34:08,219
kumbuka katika orodha moja-urefu, huwezi kurudi nyuma.

564
00:34:08,219 --> 00:34:13,659
Hivyo hii ni wazo la predptr kidole wangu wa kushoto, na newptr - si newptr.

565
00:34:13,659 --> 00:34:17,199
Mwingine pointer kwamba hapa ni kidole yangu nyingine, na mimi nina aina tu ya kutembea orodha.

566
00:34:17,199 --> 00:34:22,179
Hiyo ndiyo sababu kwamba ipo. Lakini hebu fikiria tu moja ya kesi rahisi hapa.

567
00:34:22,179 --> 00:34:26,620
Kama kwamba pointer wa shamba la pili ni null, nini maana mantiki?

568
00:34:26,620 --> 00:34:30,840
Kama wewe ni traversing orodha hii na wewe hit pointer null?

569
00:34:30,840 --> 00:34:35,780
Wewe ni mwisho wa orodha, na hivyo kanuni na kisha append hii moja ya ziada ya kipengele

570
00:34:35,780 --> 00:34:41,230
ni aina ya Intuitive itachukua kwamba nodi ambaye ijayo pointer ni null,

571
00:34:41,230 --> 00:34:46,120
hivyo hii sasa ni null, na mabadiliko hayo, ingawa, kwa kuwa na anwani ya node mpya.

572
00:34:46,120 --> 00:34:52,260
Hivyo sisi ni tu kuchora katika code mshale tulianzisha juu ya hatua kwa kuongeza mtu mkono wa kushoto.

573
00:34:52,260 --> 00:34:54,070
>> Na kesi ya kwamba mimi itabidi kukitikisa mikono yangu katika kwa sasa,

574
00:34:54,070 --> 00:34:58,020
tu kwa sababu nadhani ni rahisi kupata waliopotea wakati sisi kufanya hivyo katika hii aina ya mazingira,

575
00:34:58,020 --> 00:35:00,600
ni kuangalia kwa Infogande katika orodha ya katikati.

576
00:35:00,600 --> 00:35:03,220
Lakini tu intuitively, nini mahitaji ya kutokea kama unataka kufikiri

577
00:35:03,220 --> 00:35:06,600
ambapo idadi baadhi ni katikati ni una kutembea ni

578
00:35:06,600 --> 00:35:09,510
kwa kidole zaidi ya moja, zaidi ya moja pointer,

579
00:35:09,510 --> 00:35:12,920
takwimu nje ambapo ni kwa kuangalia ni kipengele <moja ya sasa,

580
00:35:12,920 --> 00:35:15,450
> Moja ya sasa, na mara moja kupata kwamba mahali,

581
00:35:15,450 --> 00:35:20,400
basi una kufanya aina hii ya mchezo shell ambapo wewe hoja kuyatumia kuzunguka kwa makini sana.

582
00:35:20,400 --> 00:35:23,850
Na kwamba jibu, kama Ningependa kwa sababu kwa njia hii nyumbani juu yako mwenyewe,

583
00:35:23,850 --> 00:35:28,340
majipu chini tu kwa mistari hii miwili ya kificho, lakini utaratibu wa wale mistari ni super muhimu.

584
00:35:28,340 --> 00:35:31,390
Kwa sababu kama wewe kuacha mkono wa mtu na kuongeza mtu mwingine ili makosa,

585
00:35:31,390 --> 00:35:34,580
tena, unaweza kuishia orphaning orodha.

586
00:35:34,580 --> 00:35:39,500
Kwa muhtasari zaidi conceptually, insertion katika mkia ni rahisi.

587
00:35:39,500 --> 00:35:42,940
insertion katika kichwa pia ni kiasi moja kwa moja,

588
00:35:42,940 --> 00:35:45,580
lakini unahitaji update pointer ziada wakati huu

589
00:35:45,580 --> 00:35:47,930
itapunguza idadi 5 katika orodha hapa,

590
00:35:47,930 --> 00:35:51,560
na kisha kuingizwa katika katikati inahusisha hata zaidi juhudi,

591
00:35:51,560 --> 00:35:56,130
kwa makini sana kuingiza idadi 20 katika eneo lake sahihi,

592
00:35:56,130 --> 00:35:58,350
ambayo ni kati ya 17 na 22.

593
00:35:58,350 --> 00:36:02,700
Hivyo haja ya kufanya kitu kama kuwa mwezi nodi 20 uhakika na 22,

594
00:36:02,700 --> 00:36:08,470
na kisha, pointer ambayo nodi ya mahitaji ya kuwa updated mara ya mwisho?

595
00:36:08,470 --> 00:36:10,630
Ni 17, kwa kweli kuingiza.

596
00:36:10,630 --> 00:36:14,080
Hivyo tena, mimi itabidi kuahirisha code halisi kwa ajili ya utekelezaji huo.

597
00:36:14,080 --> 00:36:17,280
>> Kwa mtazamo wa kwanza, ni kidogo mno, lakini ni kweli tu kitanzi usio

598
00:36:17,280 --> 00:36:21,770
hiyo looping, looping, looping, looping, na kuvunja haraka kama wewe hit pointer null,

599
00:36:21,770 --> 00:36:24,590
ambapo kiwango unaweza kufanya insertion zinazohitajika.

600
00:36:24,590 --> 00:36:30,960
Hii basi, ni mwakilishi wanaohusishwa orodha insertion code.

601
00:36:30,960 --> 00:36:34,590
Hiyo ilikuwa ni aina ya mengi, na anahisi kama tumekuwa kutatuliwa tatizo moja,

602
00:36:34,590 --> 00:36:36,940
lakini tumekuwa ilianzisha mzima nyingine moja. Kusema ukweli, tumekuwa alitumia muda wote huu

603
00:36:36,940 --> 00:36:40,540
juu ya kubwa O na Ω na mbio wakati, kujaribu kutatua matatizo ya haraka zaidi,

604
00:36:40,540 --> 00:36:43,270
na hapa sisi ni kuchukua hatua kubwa nyuma, anahisi.

605
00:36:43,270 --> 00:36:45,380
Na bado, kama lengo ni kuhifadhi data,

606
00:36:45,380 --> 00:36:48,010
anahisi kama Grail Mtakatifu, kama sisi alisema Jumatatu, ingekuwa kweli kuwa

607
00:36:48,010 --> 00:36:50,470
kuhifadhi vitu instantly.

608
00:36:50,470 --> 00:36:53,930
>> Kwa kweli, tuseme kwamba sisi tulikuwa kuweka kando wanaohusishwa orodha kwa muda

609
00:36:53,930 --> 00:36:56,000
na sisi badala ilianzisha dhana ya meza.

610
00:36:56,000 --> 00:36:59,110
Na hebu tu kufikiri ya meza kwa muda kama safu.

611
00:36:59,110 --> 00:37:03,790
Hii safu na kesi hii hapa ina baadhi ya vipengele 26, 0 kupitia 25,

612
00:37:03,790 --> 00:37:07,940
na kudhani kwamba zinahitajika baadhi chunk ya hifadhi kwa ajili ya majina:

613
00:37:07,940 --> 00:37:10,350
Alice na Bob na Charlie na kama.

614
00:37:10,350 --> 00:37:12,880
Na unahitaji baadhi muundo data kuhifadhi majina hayo.

615
00:37:12,880 --> 00:37:15,000
Naam, unaweza kutumia kitu kama orodha wanaohusishwa

616
00:37:15,000 --> 00:37:20,260
na unaweza kutembea orodha inserting Alice kabla Bob na Charlie baada ya Bob na kadhalika.

617
00:37:20,260 --> 00:37:23,850
Na, kwa kweli, kama unataka kuona kanuni kama kwamba kama kando,

618
00:37:23,850 --> 00:37:27,230
kujua kwamba katika list2.h, sisi kufanya hasa kwamba.

619
00:37:27,230 --> 00:37:30,610
Sisi si kwenda kwa njia ya kanuni hii, lakini hii ni lahaja ya mfano wa kwanza

620
00:37:30,610 --> 00:37:34,640
kwamba utangulizi moja nyingine struct tumeona kabla mwanafunzi kinachoitwa,

621
00:37:34,640 --> 00:37:40,330
na kisha nini ni kweli maduka katika orodha zilizounganishwa ni pointer muundo mwanafunzi

622
00:37:40,330 --> 00:37:44,520
badala ya rahisi kidogo integer, n.

623
00:37:44,520 --> 00:37:46,900
Hivyo kutambua kuna code kuna ambayo inahusisha masharti halisi,

624
00:37:46,900 --> 00:37:49,940
lakini kama lengo katika mkono kweli sasa ni kushughulikia tatizo ufanisi,

625
00:37:49,940 --> 00:37:53,380
bila kuwa nzuri kama sisi ni kupewa kitu inayoitwa Alice,

626
00:37:53,380 --> 00:37:56,020
tunataka kuweka wake katika mahali sahihi katika muundo data,

627
00:37:56,020 --> 00:37:58,860
anahisi kama ni d kuwa nzuri kwa kweli kuweka tu Alice,

628
00:37:58,860 --> 00:38:01,180
ambaye jina lake huanza na, katika mahali ya kwanza.

629
00:38:01,180 --> 00:38:05,270
Na Bob, ambaye jina lake huanza na B, katika eneo la pili.

630
00:38:05,270 --> 00:38:09,580
Na safu, au hebu kuanza kuiita meza, meza hash saa kwamba,

631
00:38:09,580 --> 00:38:13,650
tunaweza kufanya hasa ile. Kama sisi ni kupewa jina kama Alice,

632
00:38:13,650 --> 00:38:16,700
kamba kama Alice, wapi kuweka-l-i-c-e?

633
00:38:16,700 --> 00:38:20,540
Tunahitaji hueristic. Tunahitaji kazi ya kuchukua baadhi ya pembejeo kama Alice

634
00:38:20,540 --> 00:38:24,610
na kuwajibu, "Rudisha Alice katika eneo hili."

635
00:38:24,610 --> 00:38:28,720
Na kazi hii, hii sanduku nyeusi, ni kwenda kuitwa kazi hash.

636
00:38:28,720 --> 00:38:32,330
>> kazi hash ni kitu kwamba inachukua pembejeo, kama "Alice",

637
00:38:32,330 --> 00:38:38,080
na anarudi kwa wewe, kawaida, eneo numeric katika muundo baadhi data ambapo Alice ni mwanachama.

638
00:38:38,080 --> 00:38:40,830
Katika kesi hiyo, kazi yetu hash lazima rahisi kiasi.

639
00:38:40,830 --> 00:38:47,510
Kazi yetu hash lazima kusema, ikiwa wewe ni kupewa "Alice", ambayo tabia shugulike juu?

640
00:38:47,510 --> 00:38:55,660
moja ya kwanza. Hivyo mimi kuangalia [0], na kisha mimi kusema kama [0] tabia ni, kurudi idadi 0.

641
00:38:55,660 --> 00:39:01,130
Kama ni B, kurudi 1. Kama C ni, kurudi 2, na kadhalika.

642
00:39:01,130 --> 00:39:05,940
Yote index 0, na kwamba ingekuwa naomba Insert Alice na kisha Bob na kisha Charlie na kadhalika

643
00:39:05,940 --> 00:39:10,960
ndani ya muundo huu data. Lakini kuna tatizo.

644
00:39:10,960 --> 00:39:13,060
Nini kama Anita huja pamoja tena?

645
00:39:13,060 --> 00:39:17,510
Wapi sisi kuweka Anita? Jina lake, pia, huanza na barua,

646
00:39:17,510 --> 00:39:20,330
na anahisi kama tumekuwa alifanya fujo hata kubwa ya tatizo hili.

647
00:39:20,330 --> 00:39:24,380
Sisi sasa kuwa insertion haraka, mara kwa mara wakati insertion, katika muundo wa data

648
00:39:24,380 --> 00:39:27,100
badala ya mbaya ya kesi linear,

649
00:39:27,100 --> 00:39:29,510
lakini nini tunaweza kufanya na Anita katika kesi hii?

650
00:39:29,510 --> 00:39:34,110
Je, ni chaguzi mbili, kweli? Yeah?

651
00:39:34,110 --> 00:39:37,410
[Mwanafunzi jibu, unintelligible] Sawa, hivyo tunaweza kuwa na mwingine mwelekeo.

652
00:39:37,410 --> 00:39:42,320
Hiyo ni nzuri. Hivyo tunaweza kujenga mambo ya nje katika 3D kama kuongelea maneno Jumatatu.

653
00:39:42,320 --> 00:39:46,700
Tunaweza kuongeza upatikanaji mwingine hapa, lakini tuseme kwamba hakuna, mimi nina kujaribu kuweka hii rahisi.

654
00:39:46,700 --> 00:39:50,160
Lengo zima hapa ni kuwa na haraka ya mara kwa mara-wakati upatikanaji,

655
00:39:50,160 --> 00:39:52,170
hivyo hiyo ni kuongeza sana utata.

656
00:39:52,170 --> 00:39:55,970
Je, ni chaguzi nyingine wakati akijaribu Insert Anita ndani ya muundo huu data? Yeah?

657
00:39:55,970 --> 00:39:58,610
[Mwanafunzi jibu, unintelligible] Good. Hivyo sisi inaweza hoja kila mtu mwingine chini,

658
00:39:58,610 --> 00:40:03,040
kama Charlie nudges chini Bob na Alice, na kisha sisi kuweka Anita ambapo yeye kweli anataka kuwa.

659
00:40:03,040 --> 00:40:05,660
>> Bila shaka, sasa, kuna athari ya hili.

660
00:40:05,660 --> 00:40:09,000
Hii muundo data pengine ni muhimu si kwa sababu tunataka Insert watu mara moja

661
00:40:09,000 --> 00:40:11,250
lakini kwa sababu tunataka kuangalia kama uko huko baadaye

662
00:40:11,250 --> 00:40:13,600
kama tunataka magazeti nje yote ya majina katika muundo data.

663
00:40:13,600 --> 00:40:15,850
Sisi ni kwenda kufanya kitu kwa data hii hatimaye.

664
00:40:15,850 --> 00:40:20,810
Hivyo sasa tumekuwa aina ya Star zaidi ya Alice, ambaye tena ambapo yeye walidhani kuwa.

665
00:40:20,810 --> 00:40:23,880
Wala Bob, wala Charlie.

666
00:40:23,880 --> 00:40:26,060
Hivyo labda hii si wazo nzuri.

667
00:40:26,060 --> 00:40:28,830
Lakini kwa kweli, hii ni chaguo moja. Tunaweza kuhama kila mtu chini,

668
00:40:28,830 --> 00:40:32,240
au heck, Anita alikuja marehemu kwa mchezo, kwa nini sio sisi tu ya kuweka Anita

669
00:40:32,240 --> 00:40:35,870
si hapa, si hapa, si hapa, hebu tu kuweka wake mdogo punde katika orodha.

670
00:40:35,870 --> 00:40:38,680
Lakini basi tatizo hili kuanza kukabidhi tena.

671
00:40:38,680 --> 00:40:41,630
Unaweza kuwa na uwezo wa kupata Alice instantly, kwa kuzingatia jina yake ya kwanza.

672
00:40:41,630 --> 00:40:44,320
Na Bob instantly, na Charlie. Lakini basi ukiangalia kwa Anita,

673
00:40:44,320 --> 00:40:46,360
na unaweza kuona, hmm, Alice ni katika njia.

674
00:40:46,360 --> 00:40:48,770
Vizuri, basi mimi kuangalia chini Alice. Bob si Anita.

675
00:40:48,770 --> 00:40:51,850
Charlie si Anita. Oh, kuna Anita.

676
00:40:51,850 --> 00:40:54,720
Na kama wewe kuendelea kuwa treni ya mantiki njia yote,

677
00:40:54,720 --> 00:41:00,690
nini mbaya zaidi kesi mbio wakati wa kutafuta au inserting Anita ndani ya muundo huu mpya data?

678
00:41:00,690 --> 00:41:03,280
Ni O (n), sawa?

679
00:41:03,280 --> 00:41:06,280
Kwa sababu katika hali mbaya, kuna Alice, Bob, Charlie. . .

680
00:41:06,280 --> 00:41:10,150
njia yote chini kwa mtu aitwaye "Y", hivyo kuna mmoja tu doa kushoto.

681
00:41:10,150 --> 00:41:13,950
Nashiriki, hatuna moja inayoitwa "Z", hivyo sisi kuweka Anita chini sana.

682
00:41:13,950 --> 00:41:16,040
>> Sisi si kweli kwamba tatizo kutatuliwa.

683
00:41:16,040 --> 00:41:19,890
Hivyo labda hatuna haja ya kuanzisha hii dimension ya tatu.

684
00:41:19,890 --> 00:41:22,230
Na zinageuka, kama hatuwezi kuanzisha hii mwelekeo wa tatu,

685
00:41:22,230 --> 00:41:25,240
hatuwezi kufanya hii kikamilifu, lakini Grail Mtakatifu anaenda kuwa kupata

686
00:41:25,240 --> 00:41:28,370
mara kwa mara-wakati insertion na insertions nguvu ili

687
00:41:28,370 --> 00:41:30,960
hatuna kwa bidii-code safu ya ukubwa 26.

688
00:41:30,960 --> 00:41:34,400
Tunaweza Insert kama majina mengi kama tunataka, lakini hebu wetu 5-dakika kuvunja hapa

689
00:41:34,400 --> 00:41:38,790
na kisha kufanya hivyo vizuri.

690
00:41:38,790 --> 00:41:46,020
Wote haki. Mimi kuweka hadithi juu pretty artificially kuna

691
00:41:46,020 --> 00:41:48,670
kwa kuchagua Alice na kisha Bob na kisha Charlie na kisha Anita,

692
00:41:48,670 --> 00:41:51,000
ambaye jina lake ni wazi anaenda yanapogongana na Alice.

693
00:41:51,000 --> 00:41:54,120
Lakini swali sisi kumalizika Jumatatu na ni jinsi tu kinachowezekana ni

694
00:41:54,120 --> 00:41:56,370
kwamba ungependa kupata aina hii ya collisions? Kwa maneno mengine,

695
00:41:56,370 --> 00:42:00,490
kama tunataka kuanza kutumia mfumo huu tabular, ambayo ni kweli tu safu,

696
00:42:00,490 --> 00:42:02,460
katika kesi hii ya maeneo 26,

697
00:42:02,460 --> 00:42:05,740
nini kama pembejeo zetu badala enhetligt kusambazwa?

698
00:42:05,740 --> 00:42:09,620
Ni si artificially Alice na Bob na Charlie na Daudi na kadhalika alphabetically,

699
00:42:09,620 --> 00:42:12,380
ni enhetligt kusambazwa juu ya njia ya Z.

700
00:42:12,380 --> 00:42:15,220
>> Labda tutaweza tu kupata bahati na sisi siyo kwenda kuwa na mbili au mbili B

701
00:42:15,220 --> 00:42:17,640
na uwezekano juu sana, lakini kama kuna mtu alisema,

702
00:42:17,640 --> 00:42:20,730
kama sisi jumla na tatizo hili na si kufanya 0-25

703
00:42:20,730 --> 00:42:26,060
lakini, sema, 0 kupitia 364 au 65, mara nyingi idadi ya siku katika mwaka wa kawaida,

704
00:42:26,060 --> 00:42:31,170
na aliuliza swali, "Nini uwezekano kwamba sisi wawili katika chumba hiki na kuzaliwa sawa?"

705
00:42:31,170 --> 00:42:34,600
Kuweka njia nyingine, nini uwezekano kwamba mbili ya sisi kuwa na jina kwa kuanzia na?

706
00:42:34,600 --> 00:42:37,190
aina ya swali ni sawa, lakini nafasi hii anuani,

707
00:42:37,190 --> 00:42:39,940
nafasi hii tafuta, ni kubwa katika kesi ya siku za kuzaliwa,

708
00:42:39,940 --> 00:42:42,820
sababu tuna mengi zaidi ya siku katika mwaka kuliko barua katika alfabeti.

709
00:42:42,820 --> 00:42:44,910
Nini uwezekano wa mgongano?

710
00:42:44,910 --> 00:42:48,410
Naam, tunaweza kufikiria hili kwa kuhesabia math njia ya kinyume.

711
00:42:48,410 --> 00:42:50,580
Nini uwezekano wa migongano hakuna?

712
00:42:50,580 --> 00:42:53,970
Naam, hii kujieleza hapa anasema kwamba nini uwezekano

713
00:42:53,970 --> 00:42:58,770
kama kuna mtu mmoja tu katika chumba hiki, kwamba wana kuzaliwa kipekee?

714
00:42:58,770 --> 00:43:01,190
Ni 100%. Kwa sababu kama kuna mtu mmoja tu katika chumba,

715
00:43:01,190 --> 00:43:03,940
yake au siku ya kuzaliwa inaweza kuwa yoyote ya siku 365 kati ya mwaka.

716
00:43:03,940 --> 00:43:08,650
Hivyo 365/365 chaguzi anitiaye thamani ya 1.

717
00:43:08,650 --> 00:43:11,250
Hivyo uwezekano katika swali kwa sasa ni 1 tu.

718
00:43:11,250 --> 00:43:13,270
Lakini kama kuna mtu wa pili katika chumba,

719
00:43:13,270 --> 00:43:16,490
nini uwezekano kwamba kuzaliwa kwao ni tofauti?

720
00:43:16,490 --> 00:43:20,680
Kuna tu 364 iwezekanavyo siku, kupuuza leap miaka,

721
00:43:20,680 --> 00:43:23,580
kwa siku ya kuzaliwa yao si kwa yanapogongana na watu wengine.

722
00:43:23,580 --> 00:43:31,920
Hivyo 364/365. Kama mtu wa tatu unakuja, ni 363/365, na kadhalika.

723
00:43:31,920 --> 00:43:35,790
Hivyo sisi kuweka kuzidisha pamoja FRACTIONS haya, ambayo ni kupata na ndogo ndogo,

724
00:43:35,790 --> 00:43:40,720
kufikiri nini ni uwezekano kwamba sisi sote tuna kuzaliwa kipekee?

725
00:43:40,720 --> 00:43:43,570
Lakini basi tunaweza, bila shaka, kuchukua tu kwamba jibu na flip ni kuzunguka

726
00:43:43,570 --> 00:43:47,210
na kufanya 1 bala yote ya kwamba, ya kujieleza tutaweza hatimaye kupata

727
00:43:47,210 --> 00:43:51,250
kama wewe kumbuka nyuma ya vitabu yako math, inaonekana kitu kidogo kama hii,

728
00:43:51,250 --> 00:43:54,590
ambao ni muhimu sana kwa urahisi zaidi kufasiriwa graphically.

729
00:43:54,590 --> 00:43:57,820
Na hii graphic hapa ana kwenye mhimili x idadi ya siku za kuzaliwa,

730
00:43:57,820 --> 00:44:02,030
au idadi ya watu na siku za kuzaliwa, na kwenye mhimili y ni uwezekano wa mechi.

731
00:44:02,030 --> 00:44:06,060
Na nini hii ni kusema ni kwamba kama una, hebu sema, hata,

732
00:44:06,060 --> 00:44:10,860
hebu kuchagua kitu kama 22, 23.

733
00:44:10,860 --> 00:44:13,160
Kama kuna 22 au 23 watu katika chumba,

734
00:44:13,160 --> 00:44:17,100
uwezekano kwamba mbili ya wale watu wachache sana wanaenda kuwa na siku ya kuzaliwa sawa

735
00:44:17,100 --> 00:44:19,560
ni kweli super juu, combinatorially.

736
00:44:19,560 --> 00:44:23,450
50% ya tabia mbaya kwamba katika darasa la watu 22 tu, semina, kivitendo,

737
00:44:23,450 --> 00:44:25,790
2 ya watu wale ni kwenda na siku ya kuzaliwa sawa.

738
00:44:25,790 --> 00:44:28,520
Kwa sababu kuna njia nyingi ambazo unaweza kuwa na siku ya kuzaliwa sawa.

739
00:44:28,520 --> 00:44:31,110
Hata mbaya, kama ukiangalia katika upande wa kulia ya chati,

740
00:44:31,110 --> 00:44:34,040
na wakati una darasa na wanafunzi 58 katika hilo,

741
00:44:34,040 --> 00:44:39,270
uwezekano wa watu 2 ya kuwa siku ya kuzaliwa ni super, super juu, karibu asilimia 100%.

742
00:44:39,270 --> 00:44:41,880
Sasa, hiyo ni aina ya ukweli kuhusu fun maisha halisi.

743
00:44:41,880 --> 00:44:45,850
>> Lakini matokeo, sasa, kwa data miundo na hifadhi habari

744
00:44:45,850 --> 00:44:51,100
ina maana kwamba tu kuchukua una nzuri, safi, sare usambazaji wa data

745
00:44:51,100 --> 00:44:53,650
na una kubwa ya kutosha safu walionao rundo la vitu

746
00:44:53,650 --> 00:44:59,360
haina maana wewe ni kwenda kupata watu katika maeneo ya kipekee.

747
00:44:59,360 --> 00:45:03,810
Wewe utaenda kuwa na migongano. Hivyo wazo hili la hashing, kama ni kuitwa,

748
00:45:03,810 --> 00:45:07,450
kuchukua pembejeo kama "Alice" na massaging ni katika baadhi ya njia

749
00:45:07,450 --> 00:45:10,190
na kisha kupata nyuma jibu kama 0 au 1 au 2.

750
00:45:10,190 --> 00:45:17,500
Kupata nyuma baadhi ya pato kutoka kazi ambayo yanakabiliwa na uwezekano wa mgongano huu.

751
00:45:17,500 --> 00:45:19,530
Hivyo ni jinsi gani tunaweza kushughulikia migongano hizo?

752
00:45:19,530 --> 00:45:21,940
Naam, katika kesi moja, tunaweza kuchukua wazo kwamba ilipendekezwa.

753
00:45:21,940 --> 00:45:25,100
Tunaweza tu kuhama kila mtu chini, au labda zaidi kidogo tu,

754
00:45:25,100 --> 00:45:29,870
badala ya hoja ya mtu mwingine, hebu tu hoja Anita kwa chini ya doa inapatikana.

755
00:45:29,870 --> 00:45:32,810
Hivyo kama ni Alice katika 0, Bob ni katika 1, Charlie ni katika 2,

756
00:45:32,810 --> 00:45:35,260
tutaweza tu kuweka Anita katika eneo 3.

757
00:45:35,260 --> 00:45:38,860
Na hii ni mbinu katika miundo data kuitwa linear probing.

758
00:45:38,860 --> 00:45:41,310
Linear sababu wewe tu kutembea line hii, na wewe ni aina ya uchunguzi

759
00:45:41,310 --> 00:45:43,640
kwa matangazo inapatikana katika muundo data.

760
00:45:43,640 --> 00:45:46,210
Bila shaka, hii warithi katika O (n).

761
00:45:46,210 --> 00:45:49,590
Kama muundo data kweli kamili, kuna watu 25 ndani yake tayari,

762
00:45:49,590 --> 00:45:54,120
na kisha Anita huja pamoja, yeye kuishia katika nini itakuwa mahali Z, na hiyo ni faini.

763
00:45:54,120 --> 00:45:56,540
Yeye bado inafaa, na tunaweza kupata wake baadaye.

764
00:45:56,540 --> 00:46:00,100
>> Lakini hii ilikuwa kinyume na lengo la kuongeza kasi ya mambo juu.

765
00:46:00,100 --> 00:46:02,530
Basi nini kama sisi badala ilianzisha hii dimension ya tatu?

766
00:46:02,530 --> 00:46:06,400
Hiyo ni kwa ujumla mbinu kuitwa tofauti chaining, au kuwa na minyororo.

767
00:46:06,400 --> 00:46:10,030
Na nini meza hash sasa ni, muundo huu tabular,

768
00:46:10,030 --> 00:46:13,450
meza yako ni safu ya kuyatumia.

769
00:46:13,450 --> 00:46:18,230
Lakini nini wale kuyatumia uhakika na ni nadhani nini?

770
00:46:18,230 --> 00:46:21,970
orodha zinazoungwa. Basi nini kama sisi kuchukua bora wa wote wa dunia hizi?

771
00:46:21,970 --> 00:46:26,500
Sisi kutumia arrays kwa bahati ya awali

772
00:46:26,500 --> 00:46:32,070
ndani ya muundo wa data ili tuweze instantly kwenda kwenye [0] [1], [30] au kadhalika,

773
00:46:32,070 --> 00:46:36,480
lakini hivyo kwamba tuna baadhi kubadilika na tunaweza fit Anita na Alice na Adam

774
00:46:36,480 --> 00:46:38,630
na nyingine yoyote ya jina,

775
00:46:38,630 --> 00:46:43,470
sisi badala basi mhimili nyingine kukua kiholela.

776
00:46:43,470 --> 00:46:47,340
Na sisi hatimaye, kama ya Jumatatu, na kwamba uwezo expressive na orodha zilizounganishwa.

777
00:46:47,340 --> 00:46:49,530
Tunaweza kukua muundo data kiholela.

778
00:46:49,530 --> 00:46:52,450
Vinginevyo, tunaweza tu kufanya kubwa 2-dimensional safu,

779
00:46:52,450 --> 00:46:57,190
lakini kwamba itakuja kuwa hali ya kutisha kama moja ya mistari katika safu 2-dimensional

780
00:46:57,190 --> 00:47:01,280
si kubwa ya kutosha kwa ajili ya mtu ziada ambaye jina kinachotokea kwa kuanza na A.

781
00:47:01,280 --> 00:47:04,200
Mungu apishe tuna reallocate kubwa 2-dimensional muundo

782
00:47:04,200 --> 00:47:06,600
tu kwa sababu kuna watu wengi hivyo jina lake,

783
00:47:06,600 --> 00:47:09,480
hasa wakati kuna watu wachache aitwaye Z kitu.

784
00:47:09,480 --> 00:47:12,170
Ni tu kwenda sana sparse data muundo.

785
00:47:12,170 --> 00:47:15,400
Hivyo si kamilifu kwa njia yoyote, lakini sasa sisi angalau kuwa na uwezo

786
00:47:15,400 --> 00:47:19,090
instantly kupata ambapo Alice au Anita ni,

787
00:47:19,090 --> 00:47:21,090
angalau katika suala la mhimili wima,

788
00:47:21,090 --> 00:47:25,850
na kisha sisi tu kuamua wapi kuweka Anita au Alice katika orodha hii zinazoungwa.

789
00:47:25,850 --> 00:47:32,480
Kama sisi hawajali kuhusu kuchagua mambo, jinsi ya haraka tunaweza kuingiza Alice katika muundo kama hii?

790
00:47:32,480 --> 00:47:35,370
Ni mara kwa mara wakati. Sisi index katika [0], na kama hakuna mtu huko,

791
00:47:35,370 --> 00:47:37,550
Alice huenda mwanzo wa orodha hiyo zinazoungwa.

792
00:47:37,550 --> 00:47:40,000
Lakini si kwamba mpango mkubwa. Kwa sababu kama Anita kisha huja pamoja

793
00:47:40,000 --> 00:47:42,160
baadhi Idadi ya hatua ya baadaye, ambapo gani Anita ni mali?

794
00:47:42,160 --> 00:47:45,140
Naam, [0]. OOP. Alice ni tayari katika orodha ya kuwa wanaohusishwa.

795
00:47:45,140 --> 00:47:47,760
>> Lakini kama sisi hawajali kuhusu kuchagua majina haya,

796
00:47:47,760 --> 00:47:53,580
tunaweza tu hoja juu ya Alice, Insert Anita, lakini hata hilo ni mara kwa mara wakati.

797
00:47:53,580 --> 00:47:57,010
Hata kama kuna Alice na Adamu na mengine yote haya majina,

798
00:47:57,010 --> 00:47:59,410
siyo kweli shifting yao kimwili. Kwa nini?

799
00:47:59,410 --> 00:48:04,090
Kwa sababu sisi tu alifanya hapa kwa orodha wanaohusishwa, ambaye anajua walikuwa hawa nodes ni anyway?

800
00:48:04,090 --> 00:48:06,550
Wote una kufanya ni hoja makombo chakula.

801
00:48:06,550 --> 00:48:10,930
Hoja ya mishale kote; huna kimwili hoja data yoyote duniani.

802
00:48:10,930 --> 00:48:14,610
Hivyo tunaweza kuingiza Anita, katika kesi hiyo, instantly. Mara kwa mara wakati.

803
00:48:14,610 --> 00:48:20,250
Hivyo tuna mara kwa mara-wakati Luke, na mara kwa mara-wakati insertion ya mtu kama Anita.

804
00:48:20,250 --> 00:48:22,740
Lakini aina ya oversimplifying dunia.

805
00:48:22,740 --> 00:48:28,510
Nini kama sisi baadaye unataka kupata Alice?

806
00:48:28,510 --> 00:48:31,050
Nini kama sisi baadaye unataka kupata Alice?

807
00:48:31,050 --> 00:48:35,690
Jinsi hatua nyingi ni kwamba kwenda kuchukua?

808
00:48:35,690 --> 00:48:37,850
[Mwanafunzi jibu, unintelligible]

809
00:48:37,850 --> 00:48:40,950
Hasa. idadi ya watu kabla ya Alice katika orodha zinazoungwa.

810
00:48:40,950 --> 00:48:45,420
Hivyo si kabisa kamilifu, kwa sababu data muundo wetu, tena, ana hili upatikanaji wima

811
00:48:45,420 --> 00:48:50,240
na basi ina orodha hizi zilizounganishwa kunyongwa - kweli, basi si kuteka ni safu.

812
00:48:50,240 --> 00:48:56,020
Ni haya orodha wanaohusishwa kunyongwa mbali ya hiyo kwamba inaonekana kitu kidogo kama hii.

813
00:48:56,020 --> 00:48:59,110
Lakini tatizo ni kama Alice na Adamu na mengine yote haya majina

814
00:48:59,110 --> 00:49:01,720
kuishia zaidi na zaidi zaidi ya hapo,

815
00:49:01,720 --> 00:49:04,810
kutafuta mtu unaweza kuishia kuchukua rundo la hatua,

816
00:49:04,810 --> 00:49:06,670
bcause una traverse orodha zilizounganishwa,

817
00:49:06,670 --> 00:49:08,090
ambayo ni operesheni linear.

818
00:49:08,090 --> 00:49:14,270
Hivyo kweli, basi, wakati insertion hatimaye ni O (n), ambapo n ni idadi ya vipengele katika orodha.

819
00:49:14,270 --> 00:49:21,780
Kugawanywa na, hebu kiholela kuiita m, ambapo m ni idadi ya orodha zilizounganishwa

820
00:49:21,780 --> 00:49:24,500
kwamba sisi katika mhimili huu wima.

821
00:49:24,500 --> 00:49:27,180
Kwa maneno mengine, kama kweli sisi kudhani usambazaji sare ya majina,

822
00:49:27,180 --> 00:49:30,150
kabisa unrealistic. Kuna wazi zaidi ya barua baadhi kuliko wengine.

823
00:49:30,150 --> 00:49:32,580
>> Lakini kama tunasadiki kwa sasa usambazaji sare,

824
00:49:32,580 --> 00:49:37,350
na tuna n watu jumla, na m minyororo jumla

825
00:49:37,350 --> 00:49:40,630
inapatikana kwa sisi, basi urefu wa kila minyororo ya haya

826
00:49:40,630 --> 00:49:44,380
uungwana tu ni kwenda kuwa jumla, n kugawanyika kwa idadi ya minyororo.

827
00:49:44,380 --> 00:49:48,900
Hivyo n / m. Lakini hapa ni mahali ambapo tunaweza wote mathematically wajanja.

828
00:49:48,900 --> 00:49:53,030
m ni mara kwa mara, kwa sababu kuna idadi maalum ya haya.

829
00:49:53,030 --> 00:49:54,620
Utaenda kutangaza safu yako katika mwanzo,

830
00:49:54,620 --> 00:49:58,450
na sisi siyo resizing mhimili wima. Kwa ufafanuzi, kwamba anakaa fasta.

831
00:49:58,450 --> 00:50:01,220
Ni tu mhimili usawa, hivyo kusema, kwamba ni kubadilika.

832
00:50:01,220 --> 00:50:04,760
Basi kitaalam, hii ni mara kwa mara. Hivyo sasa, wakati insertion

833
00:50:04,760 --> 00:50:09,700
ni kiasi pretty O (n).

834
00:50:09,700 --> 00:50:12,410
Hivyo kwamba hana kujisikia wote kuwa bora zaidi.

835
00:50:12,410 --> 00:50:14,940
Lakini nini ni ukweli hapa? Naam, muda wote huu, kwa wiki,

836
00:50:14,940 --> 00:50:20,640
tumekuwa akisema O (n ²). O (n), 2 x n ², - n, kugawanywa na 2. . . ech.

837
00:50:20,640 --> 00:50:23,580
Ni tu n ². Lakini sasa, katika sehemu hii ya muhula,

838
00:50:23,580 --> 00:50:25,560
tunaweza kuanza kuzungumza juu ya ulimwengu halisi tena.

839
00:50:25,560 --> 00:50:31,520
Na n / m kabisa kwa kasi zaidi kuliko tu n peke yake.

840
00:50:31,520 --> 00:50:35,170
Kama una majina elfu, na wewe kuvunja yao juu katika ndoo nyingi

841
00:50:35,170 --> 00:50:37,820
ili una kumi tu ya majina katika kila moja ya minyororo ya haya,

842
00:50:37,820 --> 00:50:41,670
kabisa kutafuta mambo kumi ni kwenda kuwa kasi zaidi kuliko mambo elfu.

843
00:50:41,670 --> 00:50:43,740
Na hivyo moja ya seti ujao tatizo ni kwenda changamoto

844
00:50:43,740 --> 00:50:46,100
kufikiri kuhusu hasa kwamba hata ingawa, yeah,

845
00:50:46,100 --> 00:50:49,520
asymptotically na kihisabati, hii bado tu linear,

846
00:50:49,520 --> 00:50:51,700
ambayo sucks kwa ujumla wakati akijaribu kupata mambo.

847
00:50:51,700 --> 00:50:54,530
Katika hali halisi, ni kwenda kuwa kasi zaidi kuliko kuwa

848
00:50:54,530 --> 00:50:56,520
sababu ya kigawanyo hii.

849
00:50:56,520 --> 00:50:58,310
Na hivyo kuna tena kwenda kuwa hii biashara-off

850
00:50:58,310 --> 00:51:01,390
na mgogoro huu kati ya nadharia na ukweli,

851
00:51:01,390 --> 00:51:03,550
na moja ya knobs kuanza kugeuka katika hatua hii katika muhula

852
00:51:03,550 --> 00:51:07,510
ni zaidi ya ukweli moja kama sisi aina ya kujiandaa kwa ajili ya mwisho wa semster,

853
00:51:07,510 --> 00:51:09,280
kama sisi kuanzisha ulimwengu wa programu ya mtandao,

854
00:51:09,280 --> 00:51:11,530
ambapo kwa kweli, utendaji ni kwenda kuhesabu kwa sababu watumiaji wako ni kwenda

855
00:51:11,530 --> 00:51:14,880
kuanza kuhisi na kufahamu design maamuzi maskini.

856
00:51:14,880 --> 00:51:19,950
>> Hivyo ni jinsi gani wewe kwenda juu ya utekelezaji zilizounganishwa - hash meza na vipengele 31?

857
00:51:19,950 --> 00:51:22,600
Na mfano uliopita ilikuwa kiholela kuhusu siku za kuzaliwa.

858
00:51:22,600 --> 00:51:26,190
Kama mtu ana siku ya kuzaliwa ya Januari 1 au Februari 1, tutaweza kuwaweka katika ndoo hii.

859
00:51:26,190 --> 00:51:28,960
Kama ni ya Januari 2, 2 Februari, Machi 2, tutaweza kuwaweka katika ndoo hii.

860
00:51:28,960 --> 00:51:32,220
Hiyo ndiyo ilikuwa 31. Jinsi gani unaweza kutangaza meza hash?

861
00:51:32,220 --> 00:51:37,480
Inaweza kuwa pretty rahisi, nodi * meza ni jina langu holela kwa ajili yake, [31].

862
00:51:37,480 --> 00:51:42,400
Hii inanipa kuyatumia 31 kwa nodes,

863
00:51:42,400 --> 00:51:45,370
na kwamba inaruhusu yangu kuwa kuyatumia 31 kwa orodha wanaohusishwa

864
00:51:45,370 --> 00:51:48,800
hata kama wale minyororo ni awali null.

865
00:51:48,800 --> 00:51:54,860
Nini nataka kuweka kama nataka kuhifadhi "Alice," "Bob," "Charlie"?

866
00:51:54,860 --> 00:51:57,010
Naam, tunahitaji wrap mambo hayo katika muundo

867
00:51:57,010 --> 00:52:00,530
sababu tunahitaji Alice kwa uhakika na Bob, kwa uhakika na Charlie, na kadhalika.

868
00:52:00,530 --> 00:52:04,940
Hatuwezi tu majina peke yake, ili niweze kujenga muundo mpya iitwayo nodi hapa.

869
00:52:04,940 --> 00:52:08,310
>> Nini ni nodi halisi? Nini ni nodi katika orodha hii mpya wanaohusishwa?

870
00:52:08,310 --> 00:52:11,840
Jambo la kwanza, iitwayo neno, ni kwa jina la mtu.

871
00:52:11,840 --> 00:52:14,340
LENGTH, labda, inahusiana na upeo wa urefu wa jina binadamu,

872
00:52:14,340 --> 00:52:18,210
chochote kile, 20, 30, 40 wahusika katika kesi mambo kona,

873
00:52:18,210 --> 00:52:22,680
na 1 ni kwa nini? Ni tu ni ziada null tabia, \ 0.

874
00:52:22,680 --> 00:52:27,410
Hivyo nodi hii wrapping "kitu" ndani ya yenyewe,

875
00:52:27,410 --> 00:52:29,640
lakini pia inatangaza pointer iitwayo ijayo

876
00:52:29,640 --> 00:52:32,580
ili tuweze mnyororo Alice kwa Bob kwa Charlie na kadhalika.

877
00:52:32,580 --> 00:52:36,700
Inaweza kuwa null lakini siyo lazima kuwa.

878
00:52:36,700 --> 00:52:40,110
Maswali yoyote juu ya mbao hizo hash? Yeah?

879
00:52:40,110 --> 00:52:46,190
[Mwanafunzi kuuliza swali, unintelligible] safu - nzuri swali.

880
00:52:46,190 --> 00:52:50,120
Kwa nini hii ni neno Char katika safu badala tu ya Char *?

881
00:52:50,120 --> 00:52:53,830
Katika mfano huu kwa kiasi fulani holela, mimi sitaki kuwa na kuamua

882
00:52:53,830 --> 00:52:56,190
kwa malloc kwa kila moja ya majina ya awali.

883
00:52:56,190 --> 00:52:59,530
Nilitaka kutangaza kiasi cha upeo wa kumbukumbu kwa kamba

884
00:52:59,530 --> 00:53:06,020
ili niweze nakala katika muundo Alice \ 0 na si kuwa na kushughulika na malloc na bure na kama.

885
00:53:06,020 --> 00:53:11,710
Lakini mimi naweza kufanya kwamba kama nilitaka kuwa zaidi ufahamu wa matumizi ya nafasi. Nzuri swali.

886
00:53:11,710 --> 00:53:14,780
Basi hebu jaribu kujumlisha mbali haya

887
00:53:14,780 --> 00:53:18,350
na kuzingatia salio ya leo kwenye miundo ya data zaidi kwa ujumla

888
00:53:18,350 --> 00:53:21,170
na matatizo mengine ya kwamba tunaweza kutatua kutumia misingi sawa

889
00:53:21,170 --> 00:53:24,590
ingawa miundo data wenyewe ili tofauti katika maelezo yao.

890
00:53:24,590 --> 00:53:27,910
>> Hivyo zinageuka katika sayansi ya kompyuta, miti ni ya kawaida sana.

891
00:53:27,910 --> 00:53:29,760
Na unaweza kufikiria aina ya mti kama mti wa familia,

892
00:53:29,760 --> 00:53:31,830
ambapo kuna baadhi ya mizizi, baadhi matriarch au dume,

893
00:53:31,830 --> 00:53:34,540
bibi au babu au mapema nyuma,

894
00:53:34,540 --> 00:53:38,880
zipitazo ni mama na baba au ndugu mbalimbali au kama.

895
00:53:38,880 --> 00:53:42,500
Hivyo muundo mti ina nodes na ana watoto,

896
00:53:42,500 --> 00:53:45,260
kawaida 0 au zaidi ya watoto kwa kila node.

897
00:53:45,260 --> 00:53:47,320
Na baadhi ya jargon kwamba unaweza kuona katika picha hii hapa

898
00:53:47,320 --> 00:53:50,630
ni mojawapo ya watoto wadogo au grandkids pembeni

899
00:53:50,630 --> 00:53:52,330
ambao wana mishale hakuna vikiwemo kutoka kwao,

900
00:53:52,330 --> 00:53:55,070
wale ni majani kinachojulikana, na mtu yeyote juu ya ndani ya

901
00:53:55,070 --> 00:53:58,790
ni nodi ndani; unaweza kuiita chochote pamoja wale mistari.

902
00:53:58,790 --> 00:54:01,430
Lakini muundo huu ni pretty kawaida. Hii moja ni kidogo kiholela.

903
00:54:01,430 --> 00:54:04,930
Tuna mtoto mmoja upande wa kushoto, tuna watoto watatu juu ya haki,

904
00:54:04,930 --> 00:54:06,830
watoto wawili juu ya chini kushoto.

905
00:54:06,830 --> 00:54:10,740
Ili tuweze kuwa na miti mbalimbali ya ukubwa, lakini kama sisi kuanza kwa standardize mambo,

906
00:54:10,740 --> 00:54:15,330
na unaweza kukumbuka hii kutoka video Patrick juu tafuta binary kutoka mfupi uliopita

907
00:54:15,330 --> 00:54:19,490
online, tafuta binary haina kutekelezwa na safu

908
00:54:19,490 --> 00:54:21,410
au vipande vya karatasi juu ya ubao.

909
00:54:21,410 --> 00:54:25,490
Tuseme kwamba ulitaka kuhifadhi nambari yako katika muundo kisasa zaidi data.

910
00:54:25,490 --> 00:54:27,680
Unaweza kuunda mti kama huu.

911
00:54:27,680 --> 00:54:35,290
Unaweza kuwa na nodi alitangaza katika C, na node ya kwamba unaweza kuwa na vipengele angalau mbili ndani yake.

912
00:54:35,290 --> 00:54:39,470
Moja ni idadi unataka kuhifadhi, na nyingine ni - vizuri, tunahitaji moja zaidi.

913
00:54:39,470 --> 00:54:41,540
nyingine ni watoto wake.

914
00:54:41,540 --> 00:54:45,150
Hivyo hapa ni mwingine muundo data. Wakati huu, nodi hufafanuliwa kama hifadhi ya idadi n

915
00:54:45,150 --> 00:54:49,060
na kisha kuyatumia mbili; kushoto mtoto na mtoto wa kulia.

916
00:54:49,060 --> 00:54:52,100
Na wao siyo holela. Nini kuvutia kuhusu mti huu?

917
00:54:52,100 --> 00:55:00,550
>> Nini mfano katika jinsi tumekuwa kuweka hii nje au jinsi Patrick nieleza katika video yake?

918
00:55:00,550 --> 00:55:02,790
Ni aina ya dhahiri kwamba kuna baadhi ya kuchagua kinachoendelea hapa,

919
00:55:02,790 --> 00:55:04,460
lakini nini utawala rahisi? Yeah?

920
00:55:04,460 --> 00:55:08,350
[Mwanafunzi jibu, unintelligible]

921
00:55:08,350 --> 00:55:12,040
Perfect. Kama mtazamo saa hii, unaweza kuona idadi ndogo upande wa kushoto,

922
00:55:12,040 --> 00:55:14,690
kubwa idadi ya juu kushoto, lakini hiyo ni kweli kwa kila nodi.

923
00:55:14,690 --> 00:55:20,370
Kwa kila node, mtoto wake wa kushoto chini ya hilo, na mtoto wake wa kulia zaidi kuliko yake.

924
00:55:20,370 --> 00:55:25,210
Nini maana ya hii sasa ni kama nataka kutafuta muundo huu data kwa, kusema, idadi 44,

925
00:55:25,210 --> 00:55:29,320
Nina kuanza katika mizizi, kwa sababu kama na wote wa miundo hii ngumu zaidi data sasa,

926
00:55:29,320 --> 00:55:31,910
sisi tu pointer jambo moja, mwanzo.

927
00:55:31,910 --> 00:55:35,010
Na katika kesi hii, ni mwanzo wa mizizi. Ni sio mwisho wa kushoto,

928
00:55:35,010 --> 00:55:39,530
ni mizizi ya muundo huu. Hivyo naona hapa ni 55, na mimi nina kuangalia kwa 44.

929
00:55:39,530 --> 00:55:41,430
Ambayo mwelekeo mimi nataka kwenda?

930
00:55:41,430 --> 00:55:45,680
Naam, mimi nataka kwenda kushoto, kwa sababu ni wazi, kwa haki ni kwenda kuwa kubwa mno.

931
00:55:45,680 --> 00:55:49,050
Hivyo taarifa hapa, wewe ni aina ya conceptually chopping mti katika nusu

932
00:55:49,050 --> 00:55:51,700
kwa sababu wewe kamwe kwenda chini ya upande wa kulia.

933
00:55:51,700 --> 00:55:55,410
Hivyo, kwa sasa nakwenda 55-33. Ni ndogo sana ya idadi.

934
00:55:55,410 --> 00:56:01,590
Mimi nina kuangalia kwa 44, lakini sasa mimi kujua kama ni 44 katika mti huu, naweza kwenda wazi kwa haki.

935
00:56:01,590 --> 00:56:04,460
Hivyo tena, mimi nina kupogoa miti katika nusu.

936
00:56:04,460 --> 00:56:06,780
Ni pretty much kufanana conceptually kwa kitabu cha simu.

937
00:56:06,780 --> 00:56:09,510
Ni kufanana na kile sisi alivyofanya kwa karatasi ubaoni,

938
00:56:09,510 --> 00:56:13,940
lakini ni muundo kisasa zaidi ambayo inaruhusu sisi kwa kweli kufanya

939
00:56:13,940 --> 00:56:16,880
hii kugawanya na kushinda kwa kubuni ya algorithm,

940
00:56:16,880 --> 00:56:19,420
na kwa kweli, traversing muundo kama hii - Lo.

941
00:56:19,420 --> 00:56:22,870
Traversing muundo kama hii, ambapo ni tu "kwenda njia hii au kwenda kwa njia hiyo,"

942
00:56:22,870 --> 00:56:26,870
maana kificho kwamba yote bent akili yako kwa mara ya kwanza wakati utekelezaji katika sehemu

943
00:56:26,870 --> 00:56:31,270
au kutembea njia hiyo ya nyumbani, kwa ajili ya kutafuta binary, kwa kutumia recursion au iteration,

944
00:56:31,270 --> 00:56:35,060
ni maumivu ya shingo. Kupata kipengele katikati, kisha kufanya rounding yako juu au chini.

945
00:56:35,060 --> 00:56:39,230
>> Kuna uzuri kwa hili kwa sababu sisi sasa unaweza kutumia recursion tena,

946
00:56:39,230 --> 00:56:43,760
lakini zaidi cleanly. Hakika, kama wewe ni katika idadi 55 na unataka kupata 44,

947
00:56:43,760 --> 00:56:48,450
kwenda kushoto katika kesi hii, basi nini nini? Wewe kukimbia exact algorithm.

948
00:56:48,450 --> 00:56:51,560
Wewe kuangalia thamani ya nodi, basi wewe kwenda kushoto au kulia.

949
00:56:51,560 --> 00:56:53,670
Kisha wewe kuangalia thamani ya nodi, kwenda kushoto au kulia.

950
00:56:53,670 --> 00:56:56,710
Hii ni kikamilifu inafaa kwa recursion.

951
00:56:56,710 --> 00:57:00,920
Hivyo hata kama huko nyuma tumekuwa kufanyika baadhi ya mifano uungwana holela kuwashirikisha recursion

952
00:57:00,920 --> 00:57:03,430
kwamba hakuwa na haja ya kuwa na kujirudia, na stuctures data,

953
00:57:03,430 --> 00:57:07,820
hasa miti, ni matumizi kamili ya wazo hili la kuchukua tatizo,

954
00:57:07,820 --> 00:57:12,920
kushuka, na kisha kutatua aina moja ya, lakini vidogo, mpango.

955
00:57:12,920 --> 00:57:14,590
>> Hivyo kuna mwingine muundo data kwamba tunaweza kuanzisha.

956
00:57:14,590 --> 00:57:18,760
Hii moja ni iliyoundwa katika mtazamo wa kwanza kuangalia cryptic, lakini hii ni ajabu.

957
00:57:18,760 --> 00:57:25,090
Hivyo hii ni muundo data kuitwa trie, trie, ambayo ni kurithiwa kutoka retrieval neno,

958
00:57:25,090 --> 00:57:30,210
ambayo si hutamkwa re-kujaribu-Val, lakini kwamba ni nini dunia wito mambo haya. Anajaribu. T-r-i-e.

959
00:57:30,210 --> 00:57:35,190
Ni muundo mti wa aina fulani, lakini kila mmoja wa nodi katika trie

960
00:57:35,190 --> 00:57:41,280
inaonekana kuwa nini? Na hii ni kidogo kupotosha kwa sababu ni aina ya abbreviated.

961
00:57:41,280 --> 00:57:45,960
Lakini inaonekana kama kila nodi katika trie hii ni kweli safu.

962
00:57:45,960 --> 00:57:48,840
Na hata kama mwandishi wa mchoro huu haijaonyesha hiyo,

963
00:57:48,840 --> 00:57:54,130
katika kesi hii, trie hii ni muundo data ambao lengo katika maisha ni ya kuhifadhi maneno

964
00:57:54,130 --> 00:57:57,330
kama-l-i-c-e au B-o-b.

965
00:57:57,330 --> 00:58:02,480
Na njia ambayo hiki data maduka Alice na Bob na Charlie na Anita na kadhalika

966
00:58:02,480 --> 00:58:06,970
ni inatumia safu ambapo kuhifadhi Alice katika trie,

967
00:58:06,970 --> 00:58:09,820
sisi kuanza nodi katika mizizi ambayo inaonekana kama safu,

968
00:58:09,820 --> 00:58:12,080
na ni kuandikwa katika nukuu shorthand.

969
00:58:12,080 --> 00:58:15,070
mwandishi omitted abcdefg kwa sababu kulikuwa hakuna majina na kwamba.

970
00:58:15,070 --> 00:58:19,150
Wao tu ilionyesha M na P na T, lakini katika kesi hii,

971
00:58:19,150 --> 00:58:22,780
hebu kuondokana na Alice na Bob na Charlie kwa majina baadhi ya kwamba ni hapa.

972
00:58:22,780 --> 00:58:25,670
Maxwell ni kweli katika mchoro huu.

973
00:58:25,670 --> 00:58:29,570
Hivyo ni jinsi gani kuhifadhi mwandishi M--x-w-e-l-l?

974
00:58:29,570 --> 00:58:36,990
Yeye au yeye kuanza nodi katika mizizi, na akaenda [M], hivyo takribani 13, eneo ya 13 katika safu.

975
00:58:36,990 --> 00:58:40,750
Halafu kutoka hapo, kuna pointer.

976
00:58:40,750 --> 00:58:42,760
pointer kuongoza safu nyingine.

977
00:58:42,760 --> 00:58:47,880
Kutoka huko mwandishi indexed katika safu kwamba katika eneo, kama alivyoonyeshwa huko juu kushoto,

978
00:58:47,880 --> 00:58:52,250
na kisha yeye au yeye ikifuatiwa kuwa pointer safu mwingine,

979
00:58:52,250 --> 00:58:55,460
na akaenda katika eneo pointer X.

980
00:58:55,460 --> 00:58:59,840
Kisha katika safu ijayo mahali W, E, L, L, na kadhalika,

981
00:58:59,840 --> 00:59:03,090
na hatimaye, hebu kweli kujaribu kuweka picha hii.

982
00:59:03,090 --> 00:59:05,380
Gani kuangalia nodi kama katika code?

983
00:59:05,380 --> 00:59:11,820
nodi katika trie ina safu ya kuyatumia kwa nodes zaidi.

984
00:59:11,820 --> 00:59:16,090
Lakini kuna pia got kuwa baadhi ya aina ya thamani ya bulin, angalau katika utekelezaji huu.

985
00:59:16,090 --> 00:59:18,770
Mimi kutokea kwa kuiita is_word. Kwa nini?

986
00:59:18,770 --> 00:59:22,670
Kwa sababu wakati wewe ni kuingiza Maxwell, wewe si inserting

987
00:59:22,670 --> 00:59:25,300
kitu chochote ndani ya muundo huu data.

988
00:59:25,300 --> 00:59:27,480
Wewe si kuandika M. Wewe si kuandika X.

989
00:59:27,480 --> 00:59:30,240
Wote wewe kufanya ni kufuatia kuyatumia.

990
00:59:30,240 --> 00:59:33,360
pointer kwamba inawakilisha M, basi pointer kwamba inawakilisha,

991
00:59:33,360 --> 00:59:36,310
kisha pointer kwamba inawakilisha X, kisha W, E, L, L,

992
00:59:36,310 --> 00:59:41,950
lakini nini unahitaji kufanya mwishoni ni aina ya kwenda, angalia, mimi kufikiwa hii mahali.

993
00:59:41,950 --> 00:59:45,560
Kulikuwa na neno kwamba mwisho hapa katika muundo data.

994
00:59:45,560 --> 00:59:48,190
>> Basi nini trie ni kweli kujazwa na mwandishi alichagua kuwakilisha

995
00:59:48,190 --> 00:59:51,880
haya terminuses na pembetatu kidogo.

996
00:59:51,880 --> 00:59:56,470
Hii ina maana kwamba tu ukweli pembetatu hii hapa, hii thamani ya kweli ya bulin

997
00:59:56,470 --> 00:59:59,200
ina maana kama wewe kurudi nyuma katika mti,

998
00:59:59,200 --> 01:00:02,420
kwamba maana ya neno aitwaye Maxwell ni katika hili.

999
01:00:02,420 --> 01:00:04,870
Lakini foo neno, kwa mfano,

1000
01:00:04,870 --> 01:00:07,970
si katika mti, kwa sababu kama mimi kuanza nodi katika mizizi hapa juu kwa juu,

1001
01:00:07,970 --> 01:00:14,030
Hakuna pointer f, hakuna pointer o, hakuna pointer o. Foo si jina katika kamusi hii.

1002
01:00:14,030 --> 01:00:22,460
Lakini kwa kulinganisha, Turing, t-u-r-i-n-g. Tena, sikuweza kuhifadhi t au u au r au i au n au g.

1003
01:00:22,460 --> 01:00:29,820
Lakini mimi kuhifadhi katika muundo huu data thamani ya njia ya kweli chini hapa kwenye nodi huu - kwa mti

1004
01:00:29,820 --> 01:00:33,030
kwa kuweka thamani hii bulin ya is_word kwa kweli.

1005
01:00:33,030 --> 01:00:35,740
Hivyo trie ni aina gani ya muundo huu kuvutia sana meta,

1006
01:00:35,740 --> 01:00:39,810
ambapo wewe si kweli kuhifadhi maneno yenyewe kwa aina hii ya kamusi.

1007
01:00:39,810 --> 01:00:45,100
Kuwa wazi, wewe tu kuhifadhi ndiyo au hapana, kuna neno kwamba mwisho hapa.

1008
01:00:45,100 --> 01:00:46,430
>> Sasa nini maana?

1009
01:00:46,430 --> 01:00:51,120
Kama una maneno 150,000 katika kamusi ya kwamba wewe ni kujaribu kuhifadhi kumbukumbu katika

1010
01:00:51,120 --> 01:00:53,400
kutumia kitu kama orodha wanaohusishwa,

1011
01:00:53,400 --> 01:00:56,870
wewe ni kwenda na nodes 150,000 katika orodha yako zinazoungwa.

1012
01:00:56,870 --> 01:01:00,250
Na kutafuta mtu wa maneno hayo alphabetically inaweza kuchukua O (n) wakati.

1013
01:01:00,250 --> 01:01:04,370
Linear wakati. Lakini katika kesi ya hapa trie,

1014
01:01:04,370 --> 01:01:09,210
nini wakati mbio za kutafuta neno?

1015
01:01:09,210 --> 01:01:17,390
Ni zinageuka uzuri hapa ni kwamba hata kama una 149,999 maneno tayari katika kamusi hii,

1016
01:01:17,390 --> 01:01:20,170
kama kutekelezwa kwa muundo huu data,

1017
01:01:20,170 --> 01:01:25,560
kiasi gani wakati gani kuchukua kupata au Insert moja zaidi mtu ndani ya kwamba, kama Alice, Alice?

1018
01:01:25,560 --> 01:01:30,640
Naam, ni 5 tu, labda 6 hatua kwa ajili ya tabia trailing.

1019
01:01:30,640 --> 01:01:32,880
Kwa sababu presense ya majina mengine katika muundo

1020
01:01:32,880 --> 01:01:35,340
haina kupata njia ya kuingiza Alice.

1021
01:01:35,340 --> 01:01:39,640
Aidha, kutafuta Alice mara moja kuna maneno 150,000 katika kamusi hii

1022
01:01:39,640 --> 01:01:41,960
haina kupata njia yako ya kutafuta Alice wakati wote,

1023
01:01:41,960 --> 01:01:46,880
kwa sababu ni Alice. . . . . hapa, kwa sababu nimeona thamani ya bulin.

1024
01:01:46,880 --> 01:01:50,920
Na kama hakuna bulin kweli, basi ni Alice si katika muundo huu data ya maneno.

1025
01:01:50,920 --> 01:01:56,220
Kwa maneno mengine, wakati mbio za kutafuta mambo na kuingiza mambo katika hii mpya

1026
01:01:56,220 --> 01:02:01,920
data muundo wa trie ni O ya - ni si n.

1027
01:02:01,920 --> 01:02:05,730
Kwa sababu presense ya watu 150,000 ina hakuna athari kwenye Alice, inaonekana.

1028
01:02:05,730 --> 01:02:11,560
Basi hebu kuiita k, ambapo k ni upeo wa urefu wa neno katika lugha ya Kiingereza

1029
01:02:11,560 --> 01:02:14,050
ambayo ni kawaida hakuna zaidi ya 20-kitu wahusika.

1030
01:02:14,050 --> 01:02:17,940
Hivyo k ni mara kwa mara. Hivyo Grail Mtakatifu sisi wanaonekana kuwa kupatikana sasa

1031
01:02:17,940 --> 01:02:26,000
ni kwamba wakati wa trie, mara kwa mara kwa ajili ya kuwekeza, kwa lookups, kwa kufuta maneno.

1032
01:02:26,000 --> 01:02:29,170
Kwa sababu idadi ya mambo tayari katika muundo,

1033
01:02:29,170 --> 01:02:32,600
ambayo ni hata kimwili huko. Tena, wao ni tu aina ya checked mbali, ndiyo au hapana,

1034
01:02:32,600 --> 01:02:35,050
haina athari yoyote kwa wakati wake baadaye mbio.

1035
01:02:35,050 --> 01:02:37,940
>> Lakini kuna got kuwa samaki, vinginevyo tusingeweza kupita muda kiasi

1036
01:02:37,940 --> 01:02:41,460
juu ya miundo haya mengine yote data tu na hatimaye kupata kwa moja siri hiyo ni ajabu.

1037
01:02:41,460 --> 01:02:46,410
Basi nini bei ni sisi kulipa ili kufikia ukuu hapa? Nafasi.

1038
01:02:46,410 --> 01:02:49,010
Jambo hili ni kubwa. Na sababu ya kuwa mwandishi

1039
01:02:49,010 --> 01:02:52,400
haijawasilisha hapa, taarifa kwamba mambo yote haya ili kuangalia kama arrays,

1040
01:02:52,400 --> 01:02:55,400
hakuwa kuteka ya mapumziko ya mti, wengine wa trie,

1041
01:02:55,400 --> 01:02:58,060
kwa sababu wao ni si tu muhimu kwa hadithi.

1042
01:02:58,060 --> 01:03:01,870
Lakini yote ya nodi hiyo ni super pana, na kila nodi katika mti inachukua hadi

1043
01:03:01,870 --> 01:03:07,780
26 au kweli, inaweza kuwa 27 wahusika kwa sababu katika kesi hii nilikuwa pamoja na nafasi kwa apostrophe

1044
01:03:07,780 --> 01:03:09,980
hivyo kwamba tunaweza kuwa na maneno apostrophized.

1045
01:03:09,980 --> 01:03:14,450
Katika kesi hiyo, hizi ni pana arrays. Hivyo hata kama wao siyo picutured,

1046
01:03:14,450 --> 01:03:18,190
hii inachukua hadi kiasi kikubwa cha RAM.

1047
01:03:18,190 --> 01:03:20,670
Ambayo inaweza kuwa faini, especilly katika vifaa vya kisasa,

1048
01:03:20,670 --> 01:03:25,650
lakini hiyo ni tradeoff. Sisi kupata muda kidogo kwa kutumia zaidi nafasi.

1049
01:03:25,650 --> 01:03:28,580
Hivyo ambapo ni hii yote kwenda?

1050
01:03:28,580 --> 01:03:32,640
Naam, hebu kufanya - hebu angalia hapa.

1051
01:03:32,640 --> 01:03:39,510
Hebu kufanya kuruka kwa guy hii hapa.

1052
01:03:39,510 --> 01:03:43,450
>> Amini au sio, fun kama vile C imekuwa kwa muda mrefu sasa,

1053
01:03:43,450 --> 01:03:48,130
sisi ni kufikia hatua katika muhula ambapo ni wakati wa mpito kwa mambo ya kisasa zaidi.

1054
01:03:48,130 --> 01:03:50,950
Mambo katika ngazi ya juu. Na hata kama kwa michache ijayo ya wiki

1055
01:03:50,950 --> 01:03:54,580
tutaweza bado wanaendelea kutumbukiza wenyewe katika dunia ya kuyatumia na usimamizi kumbukumbu

1056
01:03:54,580 --> 01:03:57,210
kupata kwamba faraja ambayo tunaweza kujenga juu kisha,

1057
01:03:57,210 --> 01:04:01,270
mchezo wa mwisho ni hatimaye kuanzisha, hazijaingizwa si lugha hii.

1058
01:04:01,270 --> 01:04:03,330
Tutaweza kutumia, kama dakika 10 kuzungumza juu ya HTML.

1059
01:04:03,330 --> 01:04:05,950
Zote HTML ni ni lugha ghafi, na lugha gani ghafi ni

1060
01:04:05,950 --> 01:04:10,220
ni hayo mfululizo wa mabano wazi na mabano funge kwamba kusema 'kufanya hii koze'

1061
01:04:10,220 --> 01:04:12,000
'Kufanya hii italics' kufanya hii kujivuna. '

1062
01:04:12,000 --> 01:04:14,250
Ni wale wote kielimu ya kuvutia, lakini ni super manufaa.

1063
01:04:14,250 --> 01:04:16,650
Na hakika omnipresent siku hizi.

1064
01:04:16,650 --> 01:04:19,450
Lakini nini nguvu kuhusu dunia ya HTML, na mtandao programu kwa ujumla zaidi,

1065
01:04:19,450 --> 01:04:25,910
ni kujenga mambo ya nguvu; kuandika code katika lugha kama PHP au chatu au Ruby au Java au C #.

1066
01:04:25,910 --> 01:04:30,360
Kweli, yo lugha yako ya uchaguzi ni, na kuzalisha HTML dynamically.

1067
01:04:30,360 --> 01:04:32,960
Kuzalisha kitu kinachoitwa CSS dynamically.

1068
01:04:32,960 --> 01:04:35,810
Kuachia mtindo shuka, ambayo pia ni kuhusu aesthetics.

1069
01:04:35,810 --> 01:04:41,360
Na hata ingawa, leo, kama mimi kwenda kwa baadhi ya tovuti kama Google.com utambuzi,

1070
01:04:41,360 --> 01:04:46,100
na mimi kwenda kuona, developer, mtazamo chanzo, ambayo labda umefanya kosa kabla,

1071
01:04:46,100 --> 01:04:49,800
lakini kwenda kuona chanzo, stuff pengine hii inaonekana pretty cryptic.

1072
01:04:49,800 --> 01:04:55,320
Lakini hii ni code msingi ambayo kutekeleza Google.com.

1073
01:04:55,320 --> 01:04:57,940
Juu ya mwisho wa mbele. Na kweli, haya yote ni fluffy aesthetics stuff.

1074
01:04:57,940 --> 01:05:01,740
Hii ni CSS hapa juu. Kama mimi kuweka scrolling chini tutaweza kupata baadhi ya mambo rangi-coded.

1075
01:05:01,740 --> 01:05:06,890
Hii ni HTML. Code Google inaonekana kama fujo, lakini kama mimi kweli kufungua dirisha tofauti,

1076
01:05:06,890 --> 01:05:09,380
tunaweza kuona baadhi muundo huu.

1077
01:05:09,380 --> 01:05:12,640
Kama mimi kufungua hili, taarifa hapa, ni kidogo zaidi someka.

1078
01:05:12,640 --> 01:05:16,850
Sisi ni kwenda kuona kabla ya muda mrefu hii tag, [neno] ni tag,

1079
01:05:16,850 --> 01:05:23,520
HTML, kichwa, mwili, div, script, Nakala eneo hilo, span, unaozingatia, div.

1080
01:05:23,520 --> 01:05:26,770
Na hii pia ni aina ya cryptic-kuangalia katika mtazamo wa kwanza,

1081
01:05:26,770 --> 01:05:30,890
lakini wote wa fujo hii ifuatavyo ruwaza fulani, na mwelekeo wa repeatable,

1082
01:05:30,890 --> 01:05:33,850
hivyo kwamba mara sisi kupata misingi chini, wewe utakuwa na uwezo wa kuandika code kama hii

1083
01:05:33,850 --> 01:05:37,550
na kisha kuendesha code kama hii kwa kutumia bado lugha nyingine, kuitwa JavaScript.

1084
01:05:37,550 --> 01:05:40,440
Na javascript ni lugha ya kwamba anaendesha ndani ya browser

1085
01:05:40,440 --> 01:05:44,380
leo kwamba sisi kutumia juu ya Harvard kozi, kwa chombo bila shaka ununuzi kwamba anatumia Google ramani

1086
01:05:44,380 --> 01:05:48,660
kukupa rundo zima la mabadiliko, Facebook inakupa kuonyesha updates hadhi papo,

1087
01:05:48,660 --> 01:05:51,430
Twitter kuitumia kuonyesha tweets instantly.

1088
01:05:51,430 --> 01:05:53,820
Yote hii tutaanza kutumbukiza wenyewe in

1089
01:05:53,820 --> 01:05:57,190
Lakini kufika huko, tunahitaji kuelewa kitu kidogo kuhusu mtandao.

1090
01:05:57,190 --> 01:06:01,130
Hii picha ya video hapa ni dakika tu kwa muda mrefu, na hebu kudhani kwa sasa hii ni, kwa kweli,

1091
01:06:01,130 --> 01:06:08,380
jinsi Internet kazi kama teaser kwa nini kuhusu kuja. Mimi kukupa "Warriors ya Net."

1092
01:06:08,380 --> 01:06:14,720
>> [♫ Slow chorus muziki ♫]

1093
01:06:14,720 --> 01:06:20,450
[Kiume msimuliaji] Yeye alikuja na ujumbe.

1094
01:06:20,450 --> 01:06:23,770
Pamoja na itifaki ya yote peke yake.

1095
01:06:23,770 --> 01:06:37,270
[♫ Faster elektroniki muziki ♫]

1096
01:06:37,270 --> 01:06:41,330
Alikuja dunia ya mpenyo baridi, asiyejali ruta,

1097
01:06:41,330 --> 01:06:45,690
na hatari mbaya zaidi kuliko kifo.

1098
01:06:45,690 --> 01:06:55,400
Yeye ni kufunga. Yeye ni hodari. Yeye ni TCP / IP, na yeye got anwani yako.

1099
01:06:55,400 --> 01:06:59,250
Wapiganaji wa Net.

1100
01:06:59,250 --> 01:07:05,290
[Malan] Ifwatayo wiki, basi. Internet. Mtandao programu. Hii ni CS50.

1101
01:07:05,290 --> 01:07:08,290
[CS50.TV]