1 00:00:00,000 --> 00:00:00,990 2 00:00:00,990 --> 00:00:02,970 >> [Music kucheza] 3 00:00:02,970 --> 00:00:10,400 4 00:00:10,400 --> 00:00:12,550 >> DAVID J. Malan: Hii ni CS50. 5 00:00:12,550 --> 00:00:14,612 Na hii ni mwanzo wa wiki tatu. 6 00:00:14,612 --> 00:00:16,820 Hivyo sisi tumepewa mengi ya kusisimua mambo ili kufidia leo. 7 00:00:16,820 --> 00:00:20,160 Fursa nyingi kwa kujitolea juu ya hatua. 8 00:00:20,160 --> 00:00:22,780 Na hatimaye, leo ni si kuhusu kificho hata kidogo. 9 00:00:22,780 --> 00:00:24,820 Lakini ni kuhusu mawazo, na ni kuhusu algorithms, 10 00:00:24,820 --> 00:00:28,420 na kwa kweli kurejesha baadhi ya mambo ya kujifunza kutoka wiki sifuri, 11 00:00:28,420 --> 00:00:31,910 eti kukumbuka, sisi ilianzisha monstrosity hii. 12 00:00:31,910 --> 00:00:33,880 Na kukopa msukumo na kwamba, kuanza 13 00:00:33,880 --> 00:00:36,879 kutatua milele kisasa zaidi matatizo algorithmically. 14 00:00:36,879 --> 00:00:38,420 Lakini kwanza, michache ya matangazo. 15 00:00:38,420 --> 00:00:42,020 Hivyo moja, kama ungependa kujiunga Wafanyakazi CS50 na wanafunzi katika chakula cha mchana 16 00:00:42,020 --> 00:00:44,670 Ijumaa hii, wote hapa na katika Cambridge, na katika New Haven, 17 00:00:44,670 --> 00:00:48,060 tafadhali ziara kozi tovuti, ambapo URL yanaweza kupatikana. 18 00:00:48,060 --> 00:00:50,390 Hotuba hii Jumatano kuwa hapa katika Sanders. 19 00:00:50,390 --> 00:00:53,610 Itakuwa online tu, hivyo kutusikiliza katika tovuti CS50, 20 00:00:53,610 --> 00:00:55,850 kama hapa katika Cambridge au New Haven pia. 21 00:00:55,850 --> 00:00:58,110 >> Na kisha kuweka tatizo wawili Tayari ni katika mikono yako. 22 00:00:58,110 --> 00:01:03,067 Kama si dived katika bado, naomba kutoa maoni yenye maneno makali 23 00:01:03,067 --> 00:01:05,150 kwamba, hasa sasa, kama tatizo seti mapema, 24 00:01:05,150 --> 00:01:08,669 wewe kweli kufanya unataka kuanza sasa, kama si dabble kidogo juu ya mwishoni mwa wiki au kabla 25 00:01:08,669 --> 00:01:10,710 wakati wao wa kwanza kwenda nje ya Ijumaa, kwa sababu wewe utakuwa 26 00:01:10,710 --> 00:01:14,380 kupata kwamba wao ni si lazima kupata tena au zaidi changamoto kwa 27 00:01:14,380 --> 00:01:14,950 se. 28 00:01:14,950 --> 00:01:17,575 Nadhani utapata kwamba, katika ujumla, wao huwa na kuchukua takribani 29 00:01:17,575 --> 00:01:18,892 karibu sawa na kiasi cha muda. 30 00:01:18,892 --> 00:01:20,850 Lakini ni hakika inategemea juu ya mwanafunzi, na 31 00:01:20,850 --> 00:01:22,880 inategemea mawazo na ambayo wewe mbinu yake. 32 00:01:22,880 --> 00:01:24,910 Lakini invariably, wewe ni kwenda kuendesha dhidi baadhi ukuta, 33 00:01:24,910 --> 00:01:26,350 na wewe ni kwenda kugonga baadhi mdudu, na wewe tu 34 00:01:26,350 --> 00:01:27,950 si kwenda kuwa na uwezo wa kupata juu yake wakati fulani. 35 00:01:27,950 --> 00:01:31,380 Na ni hugely muhimu kwa kuwa na uwezo hatua mbali, kurudi siku inayofuata, 36 00:01:31,380 --> 00:01:35,286 kwenda masaa ya ofisi, baada ya juu CS50 Jadili au kama, kwa kweli kupata imefunguliwa. 37 00:01:35,286 --> 00:01:36,160 Hivyo kuendelea kuwa katika akili. 38 00:01:36,160 --> 00:01:40,830 Kuanzia mwanzo iwezekanavyo ni jambo bora unaweza kufanya. 39 00:01:40,830 --> 00:01:44,160 Hivyo hapa ni wapi sisi kuanza darasa, zaidi ya wiki sifuri. 40 00:01:44,160 --> 00:01:47,441 Na tunaweza kupata kujitolea hapa anisaidie kupata vipaza sauti? 41 00:01:47,441 --> 00:01:47,940 SAWA. 42 00:01:47,940 --> 00:01:48,900 Alisimama tayari. 43 00:01:48,900 --> 00:01:50,080 Kuja juu juu. 44 00:01:50,080 --> 00:01:53,707 Nadhani hiyo ni jinsi ni kwenda kufanya kazi. 45 00:01:53,707 --> 00:01:54,415 Jina lako ni nini? 46 00:01:54,415 --> 00:01:55,570 ALAN ESTRADA: Alan Estrada. 47 00:01:55,570 --> 00:01:56,778 DAVID J. Malan: Alan Estrada. 48 00:01:56,778 --> 00:01:57,910 Kuja juu juu. 49 00:01:57,910 --> 00:01:58,619 Vyema kukutana na wewe. 50 00:01:58,619 --> 00:01:59,910 ALAN ESTRADA: Nice kukutana na wewe. 51 00:01:59,910 --> 00:02:02,772 DAVID J. Malan: Na ungekuwa hapa na sisi katika wiki sifuri, bila shaka. 52 00:02:02,772 --> 00:02:03,028 ALAN ESTRADA: Nilikuwa. 53 00:02:03,028 --> 00:02:03,160 Nilikuwa. 54 00:02:03,160 --> 00:02:05,868 >> DAVID J. Malan: Hivyo inaweza kwenda mbele na kupata kwa ajili yetu Mike Smith, 55 00:02:05,868 --> 00:02:08,639 kama kufunga kama unaweza? 56 00:02:08,639 --> 00:02:10,639 Kama kufunga kama unaweza. 57 00:02:10,639 --> 00:02:13,756 Halisi kuchanika tatizo katika nusu kama unahitaji. 58 00:02:13,756 --> 00:02:15,130 >> ALAN ESTRADA: Um. 59 00:02:15,130 --> 00:02:17,380 DAVID J. Malan: Literally kuchanika tatizo katika nusu. 60 00:02:17,380 --> 00:02:20,210 61 00:02:20,210 --> 00:02:22,083 >> ALAN ESTRADA: Oh. 62 00:02:22,083 --> 00:02:22,583 Mm. 63 00:02:22,583 --> 00:02:23,300 Vizuri sana. 64 00:02:23,300 --> 00:02:23,700 >> DAVID J. Malan: Sawa. 65 00:02:23,700 --> 00:02:24,200 Nzuri. 66 00:02:24,200 --> 00:02:24,701 Asante. 67 00:02:24,701 --> 00:02:25,700 ALAN ESTRADA: vizuri sana. 68 00:02:25,700 --> 00:02:26,210 SAWA. 69 00:02:26,210 --> 00:02:27,610 >> DAVID J. Malan: Na hivyo sasa, umefanya whittled chini 70 00:02:27,610 --> 00:02:29,320 kwa nusu ya ukubwa wa tatizo. 71 00:02:29,320 --> 00:02:31,267 Sasa, sisi ni chini ya robo. 72 00:02:31,267 --> 00:02:33,475 Je, wewe ni kulipa kipaumbele kwa ambayo upande sisi ni kuweka? 73 00:02:33,475 --> 00:02:34,405 >> [Akicheka] 74 00:02:34,405 --> 00:02:35,970 >> ALAN ESTRADA: Ndiyo, mimi think-- 75 00:02:35,970 --> 00:02:37,594 >> DAVID J. Malan: Je, ni sehemu sisi katika? 76 00:02:37,594 --> 00:02:39,150 ALAN ESTRADA: Mufflers, hivyo. 77 00:02:39,150 --> 00:02:39,941 >> DAVID J. Malan: Sawa. 78 00:02:39,941 --> 00:02:42,810 Lakini Mike Smith ni kwenda kuwa baada Mufflers. 79 00:02:42,810 --> 00:02:44,130 So-- 80 00:02:44,130 --> 00:02:48,180 >> [Akicheka] 81 00:02:48,180 --> 00:02:48,742 >> Sawa. 82 00:02:48,742 --> 00:02:50,200 ALAN ESTRADA: wapi sisi kuangalia? 83 00:02:50,200 --> 00:02:52,049 DAVID J. Malan: Mike Smith. 84 00:02:52,049 --> 00:02:53,090 ALAN ESTRADA: Mike Smith. 85 00:02:53,090 --> 00:02:54,760 DAVID J. Malan: Sasa, tuko katika upasuaji. 86 00:02:54,760 --> 00:02:57,840 Sasa, waganga. 87 00:02:57,840 --> 00:02:58,340 Now-- 88 00:02:58,340 --> 00:02:59,856 >> ALAN ESTRADA: Let's- twende kwa kweli. 89 00:02:59,856 --> 00:03:00,370 Halisi. 90 00:03:00,370 --> 00:03:00,970 >> DAVID J. Malan: Real. 91 00:03:00,970 --> 00:03:01,470 SAWA. 92 00:03:01,470 --> 00:03:03,700 Kama unahitaji Real. 93 00:03:03,700 --> 00:03:05,250 Sasa, njia ambayo ni Mike Smith? 94 00:03:05,250 --> 00:03:06,250 >> ALAN ESTRADA: Kwa njia hii. 95 00:03:06,250 --> 00:03:07,333 >> DAVID J. Malan: Ni njia? 96 00:03:07,333 --> 00:03:08,240 ALAN ESTRADA: Ngoja. 97 00:03:08,240 --> 00:03:08,790 M is-- haki? 98 00:03:08,790 --> 00:03:09,110 Tulianza with-- 99 00:03:09,110 --> 00:03:10,090 >> DAVID J. Malan: Yeah. 100 00:03:10,090 --> 00:03:10,650 Wao ni kushoto. 101 00:03:10,650 --> 00:03:11,430 Wako wa kulia. 102 00:03:11,430 --> 00:03:11,710 >> ALAN ESTRADA: Naam. 103 00:03:11,710 --> 00:03:13,126 >> DAVID J. Malan: Hivyo Mike katika hapa. 104 00:03:13,126 --> 00:03:13,990 ALAN ESTRADA: nini? 105 00:03:13,990 --> 00:03:14,665 >> [Akicheka] 106 00:03:14,665 --> 00:03:17,365 107 00:03:17,365 --> 00:03:18,330 >> Mfano mbaya, nyie. 108 00:03:18,330 --> 00:03:18,830 Pole. 109 00:03:18,830 --> 00:03:21,610 DAVID J. Malan: hii kufundisha wewe ataruka nje ya mwenyekiti wako. 110 00:03:21,610 --> 00:03:22,318 >> ALAN ESTRADA: Oh. 111 00:03:22,318 --> 00:03:22,890 Loo. 112 00:03:22,890 --> 00:03:23,390 Nimekuelewa. 113 00:03:23,390 --> 00:03:24,670 Nimekuelewa. 114 00:03:24,670 --> 00:03:25,170 Loo. 115 00:03:25,170 --> 00:03:25,669 Loo. 116 00:03:25,669 --> 00:03:26,812 Hii is-- sawa, I got wewe. 117 00:03:26,812 --> 00:03:27,520 Smith hapa hapa? 118 00:03:27,520 --> 00:03:28,894 >> DAVID J. Malan: Smith, asante. 119 00:03:28,894 --> 00:03:30,535 Hivyo mimi itabidi kuweka kuangalia juu Smith? 120 00:03:30,535 --> 00:03:30,790 >> ALAN ESTRADA: Oh, yeah. 121 00:03:30,790 --> 00:03:31,340 Hapana, hapana, hapana. 122 00:03:31,340 --> 00:03:31,600 Oh, hakuna. 123 00:03:31,600 --> 00:03:31,940 Hii ni yangu. 124 00:03:31,940 --> 00:03:32,580 >> DAVID J. Malan: Oh, wewe got Smith. 125 00:03:32,580 --> 00:03:33,415 SAWA. 126 00:03:33,415 --> 00:03:34,040 >> ALAN ESTRADA: Yeah, mimi got Smith haki hapa. 127 00:03:34,040 --> 00:03:34,700 Samahani, nyie. 128 00:03:34,700 --> 00:03:35,860 Nilidhani Michael-- sisi walikuwa wanatafuta Michael. 129 00:03:35,860 --> 00:03:36,550 Pole. 130 00:03:36,550 --> 00:03:37,550 >> DAVID J. Malan: Ni sawa. 131 00:03:37,550 --> 00:03:39,950 Haki zote, sasa tuko ndani ya Paccini na Wana. 132 00:03:39,950 --> 00:03:41,242 >> ALAN ESTRADA: Paccini na wana. 133 00:03:41,242 --> 00:03:43,158 DAVID J. Malan: wewe tu na mimi ni katika juu ya hili. 134 00:03:43,158 --> 00:03:44,050 SAWA. 135 00:03:44,050 --> 00:03:45,130 Kupata sisi Mike Smith. 136 00:03:45,130 --> 00:03:45,830 Smith. 137 00:03:45,830 --> 00:03:46,310 >> ALAN ESTRADA: Smith. 138 00:03:46,310 --> 00:03:46,750 >> DAVID J. Malan: Smith. 139 00:03:46,750 --> 00:03:47,728 Tuko katika R kwa takataka. 140 00:03:47,728 --> 00:03:48,644 ALAN ESTRADA: Taka. 141 00:03:48,644 --> 00:03:50,096 Loo. 142 00:03:50,096 --> 00:03:52,480 Hii ni kwenda kuchukua muda. 143 00:03:52,480 --> 00:03:54,340 >> [Akicheka] 144 00:03:54,340 --> 00:03:55,804 145 00:03:55,804 --> 00:03:56,720 DAVID J. Malan: viatu. 146 00:03:56,720 --> 00:03:58,080 Tuko katika viatu. 147 00:03:58,080 --> 00:04:00,210 >> ALAN ESTRADA: Sasa tuko gonna-- 148 00:04:00,210 --> 00:04:01,105 >> DAVID J. Malan: Nice. 149 00:04:01,105 --> 00:04:01,980 ALAN ESTRADA: Which-- 150 00:04:01,980 --> 00:04:03,620 [Akicheka] 151 00:04:03,620 --> 00:04:05,440 Oh, hii ni kubwa. 152 00:04:05,440 --> 00:04:06,910 [Akicheka] 153 00:04:06,910 --> 00:04:08,380 154 00:04:08,380 --> 00:04:09,390 >> DAVID J. Malan: Ni sawa. 155 00:04:09,390 --> 00:04:11,365 >> ALAN ESTRADA: Oh, hii ni nzuri. 156 00:04:11,365 --> 00:04:14,425 Sidhani nina kwenda na marafiki PSAT baada ya hii. 157 00:04:14,425 --> 00:04:15,300 DAVID J. Malan: Mwema. 158 00:04:15,300 --> 00:04:16,078 Vifaa. 159 00:04:16,078 --> 00:04:17,036 ALAN ESTRADA: Vifaa. 160 00:04:17,036 --> 00:04:18,668 Um, L, M, N, O, P. 161 00:04:18,668 --> 00:04:19,459 DAVID J. Malan: Sawa. 162 00:04:19,459 --> 00:04:21,600 Basi hebu machozi huu katika nusu. 163 00:04:21,600 --> 00:04:22,270 Ni sawa. 164 00:04:22,270 --> 00:04:25,606 Hii kuishia vibaya anyway, kwa sababu Mike Smith haitakuwa katika kurasa njano. 165 00:04:25,606 --> 00:04:26,430 >> ALAN ESTRADA: Aw. 166 00:04:26,430 --> 00:04:27,140 >> DAVID J. Malan: Hapana, ni sawa. 167 00:04:27,140 --> 00:04:28,930 Lakini hebu kujifanya kama yeye ni juu ya ukurasa huu. 168 00:04:28,930 --> 00:04:33,260 Hivyo sasa, umefanya whittled tatizo chini kwa ukurasa mmoja, na sisi kupatikana Mike Smith. 169 00:04:33,260 --> 00:04:35,180 >> [Wakishangilia] 170 00:04:35,180 --> 00:04:35,757 171 00:04:35,757 --> 00:04:36,340 Sawa, asante. 172 00:04:36,340 --> 00:04:40,700 173 00:04:40,700 --> 00:04:41,200 SAWA. 174 00:04:41,200 --> 00:04:43,646 Hiyo ilikuwa ni ajabu. 175 00:04:43,646 --> 00:04:45,954 Lakini ilikuwa bado kasi kuliko tafuta linear, 176 00:04:45,954 --> 00:04:47,870 eti sisi kuanza saa mwanzo wa kitabu, 177 00:04:47,870 --> 00:04:51,210 na sisi hoja njia yetu kutoka kushoto kwenda kulia, hatimaye kutafuta Mike Smith. 178 00:04:51,210 --> 00:04:53,540 Na hivyo, kama kitabu cha simu alikuwa labda 1,000 kurasa, 179 00:04:53,540 --> 00:04:56,300 labda ingekuwa kuchukuliwa sisi 10 au hivyo ukurasa machozi. 180 00:04:56,300 --> 00:04:59,380 >> Lakini unaweza kuwa leveraged kuguswa na kudhani 181 00:04:59,380 --> 00:05:03,602 wakati yote hayo, ambayo ni kusema kwamba kitabu cha simu mapema ilikuwa nini? 182 00:05:03,602 --> 00:05:04,310 Watazamaji: Yamepangwa. 183 00:05:04,310 --> 00:05:05,000 DAVID J. Malan: Ni vyema. 184 00:05:05,000 --> 00:05:05,160 Sawa? 185 00:05:05,160 --> 00:05:07,909 Ni sorted alphabetically, hivyo kwamba wote wa majina hayo na namba 186 00:05:07,909 --> 00:05:11,230 ni sorted kutoka A kwa Z, na alphabetically katika kati ya. 187 00:05:11,230 --> 00:05:13,100 Lakini leo hii, sisi sasa kuuliza swali, vizuri, 188 00:05:13,100 --> 00:05:16,170 jinsi gani Verizon au simu kampuni kupata ndani ya hali hiyo? 189 00:05:16,170 --> 00:05:19,560 >> Kwa sababu ni jambo moja kujiinua dhana kwamba, na kwa hiyo, 190 00:05:19,560 --> 00:05:22,570 kutatua tatizo na algorithm kwa ufanisi zaidi. 191 00:05:22,570 --> 00:05:24,900 Lakini sisi kamwe kweli aliuliza katika wiki sifuri, vizuri, 192 00:05:24,900 --> 00:05:27,790 kiasi gani alifanya hivyo gharama Verizon au mtu mwingine 193 00:05:27,790 --> 00:05:29,620 kupata kwamba kitabu cha simu ili Iliyopangwa? 194 00:05:29,620 --> 00:05:29,780 >> Sawa? 195 00:05:29,780 --> 00:05:31,529 Haijalishi kama kuangalia juu Mike Smith 196 00:05:31,529 --> 00:05:35,190 ni super haraka, kama inachukua wewe mwaka wa kutatua kurasa awali. 197 00:05:35,190 --> 00:05:35,690 Sawa? 198 00:05:35,690 --> 00:05:38,620 Unaweza pia kuchuja tu kupitia randomized kitabu cha simu, 199 00:05:38,620 --> 00:05:40,690 ikiwa ni kwenda kuwa super ghali kwa aina yake. 200 00:05:40,690 --> 00:05:42,350 Hivyo kama tunaweza kuwa na kujitolea mwingine. 201 00:05:42,350 --> 00:05:46,350 Hebu kuchukua kuangalia juu hapa katika jinsi sisi might-- kuja juu up-- jinsi 202 00:05:46,350 --> 00:05:48,100 tupate kwenda juu ya kuchagua hawa. 203 00:05:48,100 --> 00:05:51,990 >> Na kama Jordan inaweza kweli kujiunga na sisi hapa juu ya hatua. 204 00:05:51,990 --> 00:05:55,100 Kuja juu juu kwa muda tu. 205 00:05:55,100 --> 00:05:56,359 Jina lako ni nini? 206 00:05:56,359 --> 00:05:57,150 CAROLINE: Caroline. 207 00:05:57,150 --> 00:05:58,691 DAVID J. Malan: Caroline, kuja juu juu. 208 00:05:58,691 --> 00:06:02,070 Na wewe utakuwa na kujiunga na na mimi na Jordan hapa. 209 00:06:02,070 --> 00:06:03,800 Caroline, asante. 210 00:06:03,800 --> 00:06:04,300 Sawa. 211 00:06:04,300 --> 00:06:08,330 Hivyo nini sisi hapa kwa Caroline ni bluu vitabu 26 212 00:06:08,330 --> 00:06:10,747 kwamba FAS anatumia kusimamia baadhi ya mwisho mitihani. 213 00:06:10,747 --> 00:06:13,330 Hizi ni kupata vigumu kupata, lakini kile ambacho tumefanya mapema 214 00:06:13,330 --> 00:06:15,800 ni kwamba tumekuwa kuweka jina la mtu mbele ya kila moja ya haya, 215 00:06:15,800 --> 00:06:18,133 lakini tumekuwa naendelea ni rahisi na kisha kuweka nje majina kamili. 216 00:06:18,133 --> 00:06:22,720 Hivyo tunataka kuweka mtu kwa jina L, D, J, B, kila njia A kupitia Z, 217 00:06:22,720 --> 00:06:24,090 lakini wao ni katika mpangilio maalum. 218 00:06:24,090 --> 00:06:26,890 Na hivyo kama wewe ungekuwa, kuzungumza yako njia tatizo kama wewe 219 00:06:26,890 --> 00:06:31,620 kufanya hivyo, unaweza kwenda mbele na aina hizi kwa ajili yetu, kutoka kwa Z. 220 00:06:31,620 --> 00:06:34,070 >> Watazamaji: OK, hivyo L ni kama, kati. 221 00:06:34,070 --> 00:06:35,050 C ni mwanzo. 222 00:06:35,050 --> 00:06:42,410 B. J kabla L. B, SWALI: 223 00:06:42,410 --> 00:06:45,140 >> DAVID J. Malan: Hold kwamba wazo kwa ajili ya pili moja. 224 00:06:45,140 --> 00:06:48,910 Kwa sababu vinginevyo, hili ni tu kuvutia na wewe, mimi, na Jordan. 225 00:06:48,910 --> 00:06:49,724 Kuna sisi kwenda. 226 00:06:49,724 --> 00:06:50,640 Watazamaji: [inaudible]. 227 00:06:50,640 --> 00:06:57,299 R. 228 00:06:57,299 --> 00:06:58,090 DAVID J. Malan: Sawa. 229 00:06:58,090 --> 00:06:59,310 Unafanya nini? 230 00:06:59,310 --> 00:07:01,730 >> CAROLINE: M inakuja baada ya O. 231 00:07:01,730 --> 00:07:02,564 >> DAVID J. Malan: Sawa. 232 00:07:02,564 --> 00:07:03,064 >> CAROLINE: O. 233 00:07:03,064 --> 00:07:04,120 DAVID J. Malan: O, Good. 234 00:07:04,120 --> 00:07:04,970 >> CAROLINE: E 235 00:07:04,970 --> 00:07:06,730 >> DAVID J. Malan: E, F. Naam. 236 00:07:06,730 --> 00:07:07,620 >> CAROLINE: T, U, V. 237 00:07:07,620 --> 00:07:10,689 >> DAVID J. Malan: V, T, U, V. Hivyo ni Inaonekana kama wewe ni making-- kuendelea. 238 00:07:10,689 --> 00:07:12,730 Inaonekana kama wewe ni kufanya rundo kubwa zaidi ya hapa, 239 00:07:12,730 --> 00:07:13,910 na aina ya rundo kubwa zaidi ya hapo. 240 00:07:13,910 --> 00:07:16,230 Hivyo nusu ya kwanza ya alfabeti, nusu ya pili ya alfabeti. 241 00:07:16,230 --> 00:07:16,460 SAWA. 242 00:07:16,460 --> 00:07:16,960 Nzuri. 243 00:07:16,960 --> 00:07:19,680 Aina ya kugawanyika tatizo katika wawili. 244 00:07:19,680 --> 00:07:21,771 M, N, X. Naam. 245 00:07:21,771 --> 00:07:22,270 CAROLINE: K. 246 00:07:22,270 --> 00:07:22,980 DAVID J. Malan: Sawa. 247 00:07:22,980 --> 00:07:25,070 K. Hivyo wewe ni aina ya kuchagua nao mmoja baada ya mwingine, 248 00:07:25,070 --> 00:07:27,620 kuweka ama upande wa kushoto au kulia, au Z kwenda juu ya sakafu. 249 00:07:27,620 --> 00:07:28,012 SAWA. 250 00:07:28,012 --> 00:07:29,190 >> CAROLINE: Z kinaendelea sakafu. 251 00:07:29,190 --> 00:07:29,360 >> DAVID J. Malan: Sawa. 252 00:07:29,360 --> 00:07:30,920 Y kinachoendelea sakafu. 253 00:07:30,920 --> 00:07:31,735 Sasa tunaweza kuweka X. 254 00:07:31,735 --> 00:07:32,409 >> CAROLINE: G. 255 00:07:32,409 --> 00:07:33,700 DAVID J. Malan: G ya kwenda kushoto. 256 00:07:33,700 --> 00:07:36,017 S ni kwenda kulia. 257 00:07:36,017 --> 00:07:37,642 Haki wote, A ni kwenda njia yote kushoto. 258 00:07:37,642 --> 00:07:38,790 >> CAROLINE: A, B, C, D. 259 00:07:38,790 --> 00:07:39,873 >> DAVID J. Malan: Sasa, nzuri. 260 00:07:39,873 --> 00:07:43,260 Sisi tumepewa, B, C. W ya kwenda chini huko. 261 00:07:43,260 --> 00:07:45,566 Sawa, T. 262 00:07:45,566 --> 00:07:46,611 >> CAROLINE: H, I, J. 263 00:07:46,611 --> 00:07:47,860 DAVID J. Malan: H, I, J. Mwema. 264 00:07:47,860 --> 00:07:49,160 CAROLINE: Katikati, mimi nina gonna-- 265 00:07:49,160 --> 00:07:50,000 DAVID J. Malan: Sawa. 266 00:07:50,000 --> 00:07:52,375 Hivyo sasa, tunakwenda aina ya kuunganisha piles hizi mbalimbali. 267 00:07:52,375 --> 00:08:00,730 Hivyo kupitia C, kisha Mimi naona D, na E, na F, na G, H na, na mimi Nice. 268 00:08:00,730 --> 00:08:05,540 J, K. Na kisha, rundo huu ni kichwa chini, lakini hiyo ni sawa. 269 00:08:05,540 --> 00:08:06,040 Uhakika. 270 00:08:06,040 --> 00:08:07,240 Tunaweza kukata baadhi pembe. 271 00:08:07,240 --> 00:08:07,950 SAWA. 272 00:08:07,950 --> 00:08:10,530 Na kisha tunahitaji W, X, Y, Z. 273 00:08:10,530 --> 00:08:11,250 >> CAROLINE: Naam. 274 00:08:11,250 --> 00:08:11,880 >> DAVID J. Malan: Mufti. 275 00:08:11,880 --> 00:08:14,122 Hivyo kubwa asante kwa Caroline kwa ajili ya kuchagua hao. 276 00:08:14,122 --> 00:08:15,030 >> [Wakishangilia] 277 00:08:15,030 --> 00:08:17,287 >> Asante. 278 00:08:17,287 --> 00:08:18,120 Asante sana. 279 00:08:18,120 --> 00:08:22,910 Hivyo sasa hebu fikiria kwa muda jinsi Caroline alikuwa anakwenda kufanya hivyo, 280 00:08:22,910 --> 00:08:26,040 na nini hasa sisi waliweza to-- jinsi sisi 281 00:08:26,040 --> 00:08:28,409 walikuwa na uwezo wa kutatua kwamba Tatizo tulipokuwa tu 282 00:08:28,409 --> 00:08:29,950 kutokana na rundo zima la pembejeo random. 283 00:08:29,950 --> 00:08:31,610 >> Naam, inaonekana kama kuna ilikuwa kidogo ya mfumo wa huko? 284 00:08:31,610 --> 00:08:32,110 Kulia. 285 00:08:32,110 --> 00:08:34,495 Hivyo barua ya awali katika alfabeti, yeye 286 00:08:34,495 --> 00:08:37,120 Ilikuwa kuweka kwa upande wa kushoto, na barua baadaye katika alfabeti, 287 00:08:37,120 --> 00:08:38,270 yeye alikuwa kuweka katika haki. 288 00:08:38,270 --> 00:08:40,500 Na haraka kama yeye amepata baadhi ya barua kupakana, ndio 289 00:08:40,500 --> 00:08:43,124 kwamba kwenda kulia karibu na kila mmoja, angeweza kuweka wale katika utaratibu. 290 00:08:43,124 --> 00:08:46,750 Na hivyo sisi aina ya alikuwa hizi ndogo marundo ya pembejeo yamepangwa kutokea. 291 00:08:46,750 --> 00:08:50,540 >> Na hivyo ndiyo kabisa kama yale wengi wetu binadamu atafanya. 292 00:08:50,540 --> 00:08:53,530 Tunataka aina ya kuchuja hilo, na tunatarajia aina ya kuwa na utaratibu. 293 00:08:53,530 --> 00:08:56,930 Lakini inaweza kuwa vigumu kuandika chini katika fomula per se. 294 00:08:56,930 --> 00:08:59,010 Ilikuwa inaonekana kikaboni kuliko ile zaidi kidogo. 295 00:08:59,010 --> 00:09:02,560 Basi hebu angalia kama tunaweza sasa amefungwa tatizo na pembejeo wachache. 296 00:09:02,560 --> 00:09:05,170 >> Badala ya 26, hebu kufanya kitu mbali wachache 297 00:09:05,170 --> 00:09:09,890 kwa kusema tu, saba, nyuma ya milango hizo, hivyo kusema. 298 00:09:09,890 --> 00:09:11,300 Je, kuna idadi saba tu? 299 00:09:11,300 --> 00:09:15,240 Na kama lengo sasa katika mkono ni kupata thamani, 300 00:09:15,240 --> 00:09:17,850 hebu angalia jinsi ufanisi tunaweza kwenda juu ya kufanya hii. 301 00:09:17,850 --> 00:09:22,460 Na hebu angalia kama tunaweza sasa kuanza kuomba idadi ya baadhi, 302 00:09:22,460 --> 00:09:26,310 au baadhi ya kanuni ambazo kueleza ufanisi wa kitabu cha simu yetu 303 00:09:26,310 --> 00:09:31,060 algorithm, kitabu mtihani wetu algorithm, na kwa ujumla zaidi, kutafuta habari. 304 00:09:31,060 --> 00:09:34,770 >> Hivyo kwa hili, basi mimi kwenda mbele, na juu ya screen kugusa zaidi ya hapa, 305 00:09:34,770 --> 00:09:41,100 kuweka kivinjari ambayo ina hasa hawa milango saba. 306 00:09:41,100 --> 00:09:46,670 Na kama tunaweza kupata mtu mwingine kujitolea kuja juu zaidi ya hapa, 307 00:09:46,670 --> 00:09:48,480 Nimekuwa kuweka milango hizo hizo zaidi ya hapa. 308 00:09:48,480 --> 00:09:49,170 Haraka kujitolea. 309 00:09:49,170 --> 00:09:51,130 >> Hii demos one-- ni kwenda kwa wepesi na haraka sasa. 310 00:09:51,130 --> 00:09:51,600 Kuja juu chini. 311 00:09:51,600 --> 00:09:52,308 Jina lako ni nini? 312 00:09:52,308 --> 00:09:53,040 TREVOR: Trevor. 313 00:09:53,040 --> 00:09:53,998 >> DAVID J. Malan: Trevor? 314 00:09:53,998 --> 00:09:55,770 Haki wote, Trevor, kuja juu chini. 315 00:09:55,770 --> 00:09:59,212 Hivyo Trevor ina alijitolea hapa kufanya tatizo sawa, lakini hiyo ni moja 316 00:09:59,212 --> 00:10:02,170 nyembamba katika upeo, na kwamba itakuja kuruhusu sisi kujaribu kurasimisha sasa 317 00:10:02,170 --> 00:10:03,970 mchakato kwa ajili ya kuchagua namba hizi. 318 00:10:03,970 --> 00:10:05,500 >> Hivyo Trevor, ni vyema kukutana na wewe. 319 00:10:05,500 --> 00:10:08,720 Hivyo hapa ni safu, hivyo kusema, orodha ya milango saba. 320 00:10:08,720 --> 00:10:10,327 Kwenda mbele na kupata yetu idadi 50. 321 00:10:10,327 --> 00:10:12,410 Na kisha baada ya ukweli, kutuambia jinsi wewe kupatikana. 322 00:10:12,410 --> 00:10:19,124 323 00:10:19,124 --> 00:10:20,040 Lazima be-- haki yote. 324 00:10:20,040 --> 00:10:21,945 Naam, hii ni moja hapa? 325 00:10:21,945 --> 00:10:24,680 Uh-oh. 326 00:10:24,680 --> 00:10:25,560 SAWA. 327 00:10:25,560 --> 00:10:26,680 Wewe clicked kwamba moja. 328 00:10:26,680 --> 00:10:28,690 Nzuri. 329 00:10:28,690 --> 00:10:29,780 >> Na nzuri. 330 00:10:29,780 --> 00:10:30,970 Sasa wewe clicked kwamba moja. 331 00:10:30,970 --> 00:10:34,060 Na nikupe kipaza sauti, ili una hiyo katika muda tu. 332 00:10:34,060 --> 00:10:37,000 Kwenda mbele na bonyeza mlango ijayo kwamba unakusudia. 333 00:10:37,000 --> 00:10:39,812 Ndiyo, nzuri. 334 00:10:39,812 --> 00:10:41,020 TREVOR: Je, mimi unclick mlango? 335 00:10:41,020 --> 00:10:42,620 DAVID J. Malan: Hapana, huwezi unclick. 336 00:10:42,620 --> 00:10:43,119 TREVOR: Sawa. 337 00:10:43,119 --> 00:10:43,974 Hii moja. 338 00:10:43,974 --> 00:10:45,640 DAVID J. Malan: wapi unataka kwenda? 339 00:10:45,640 --> 00:10:46,410 Ipi? 340 00:10:46,410 --> 00:10:47,230 >> TREVOR: moja Hiyo. 341 00:10:47,230 --> 00:10:48,042 >> DAVID J. Malan: Hapana 342 00:10:48,042 --> 00:10:48,450 >> TREVOR: Sawa. 343 00:10:48,450 --> 00:10:48,735 Hii moja. 344 00:10:48,735 --> 00:10:49,020 >> DAVID J. Malan: Ndiyo. 345 00:10:49,020 --> 00:10:49,700 Hiyo ilikuwa nzuri. 346 00:10:49,700 --> 00:10:50,380 Sawa. 347 00:10:50,380 --> 00:10:53,900 Kwa hiyo kile alikuwa algorithm yako au utaratibu wa kufanya hivyo, Trevor? 348 00:10:53,900 --> 00:10:56,149 >> TREVOR: I just akaenda kwa njia ya milango mpaka nimeona 50. 349 00:10:56,149 --> 00:10:56,940 DAVID J. Malan: Sawa. 350 00:10:56,940 --> 00:10:58,150 Bora algorithm. 351 00:10:58,150 --> 00:10:59,540 Hivyo hiyo ni nzuri. 352 00:10:59,540 --> 00:11:03,120 Kwa sababu kwa kweli, kama mimi yatangaza nini nyuma ya haya milango wengine wawili, nini 353 00:11:03,120 --> 00:11:06,954 tutaweza kupata hapa ni kwamba sisi tu random pembejeo. 354 00:11:06,954 --> 00:11:08,870 Ili kwamba ilikuwa kweli kama nzuri kama unaweza kupata. 355 00:11:08,870 --> 00:11:12,509 Na kwa kweli, wewe got bora kuliko vyema kutafuta safu nzima, 356 00:11:12,509 --> 00:11:15,300 kwa sababu ingekuwa ni kweli unlucky kama alikuwa na kugonga idadi 357 00:11:15,300 --> 00:11:16,604 50 mlangoni ya mwisho. 358 00:11:16,604 --> 00:11:18,520 Lakini sisi kama badala yale aliwapa dhana. 359 00:11:18,520 --> 00:11:20,630 Nadhani aina zote za milango hizi pande zote, 360 00:11:20,630 --> 00:11:23,500 ili una nambari yamepangwa wakati huu, 361 00:11:23,500 --> 00:11:29,730 lakini wakati huu ni kweli a different-- wakati huu, 362 00:11:29,730 --> 00:11:32,640 ni kweli yamepangwa kwa ajili yenu. 363 00:11:32,640 --> 00:11:35,380 Na sasa lengo katika mkono ni kuikumba idadi 50. 364 00:11:35,380 --> 00:11:36,090 >> TREVOR: Sawa. 365 00:11:36,090 --> 00:11:37,670 >> DAVID J. Malan: Nini algorithm yako kwenda kuwa? 366 00:11:37,670 --> 00:11:39,628 >> TREVOR: Naam, ikiwa ni yamepangwa, ni ama kwenda 367 00:11:39,628 --> 00:11:42,710 kwa be-- ikiwa kubwa kwa kubwa, kushuka, utakuwa ni moja ya kwanza, 368 00:11:42,710 --> 00:11:44,751 au kama ni kinyume, itakuwa moja ya mwisho. 369 00:11:44,751 --> 00:11:48,897 Hivyo mimi itabidi tu bomba mlango huu, na kisha tu bomba mlango mwisho. 370 00:11:48,897 --> 00:11:49,980 DAVID J. Malan: Mufti. 371 00:11:49,980 --> 00:11:50,270 Sawa. 372 00:11:50,270 --> 00:11:51,150 Hivyo sisi kupatikana idadi 50. 373 00:11:51,150 --> 00:11:52,970 Hivyo kwa haraka kama wewe alijua walikuwa yamepangwa, sisi 374 00:11:52,970 --> 00:11:55,040 walikuwa na uwezo wa kujiinua dhana hii. 375 00:11:55,040 --> 00:11:57,040 Hivyo wao ni sana kama kitabu cha simu mfano. 376 00:11:57,040 --> 00:11:59,540 Mara tu una, hata kwa Tatizo dogo kama hili, 377 00:11:59,540 --> 00:12:02,380 pembejeo yako kabla ya yamepangwa, tunaweza kweli kupata thamani arguably 378 00:12:02,380 --> 00:12:03,130 ufanisi zaidi. 379 00:12:03,130 --> 00:12:05,800 >> Na sikuweza kukuambia kama ilivyokuwa yamepangwa ndogo kwa kubwa, au kubwa kwa wadogo, 380 00:12:05,800 --> 00:12:08,080 na hivyo ilikuwa nzuri sana kuanza mwishoni moja au nyingine 381 00:12:08,080 --> 00:12:09,750 kwa kweli kupata kwamba thamani ya lengo. 382 00:12:09,750 --> 00:12:11,400 Hivyo kuwashukuru kwa Trevor pia. 383 00:12:11,400 --> 00:12:13,260 Na mimi itabidi ya kupendekeza nicely kufanyika. 384 00:12:13,260 --> 00:12:16,960 Tuna kipande cha kidogo, kwa kweli, kwamba ni miongoni mwa nyakati zetu favorite katika CS50, 385 00:12:16,960 --> 00:12:19,700 ambapo wakati mwingine demos hayo hawana kabisa kwenda kulingana na mpango. 386 00:12:19,700 --> 00:12:22,050 Na hakika hivi sasa, mimi anapigiwa interface vibaya 387 00:12:22,050 --> 00:12:23,508 na ambayo kwa kutumia touch screen. 388 00:12:23,508 --> 00:12:24,660 Ili kwamba ilikuwa kosa langu huko. 389 00:12:24,660 --> 00:12:26,600 >> Hivyo hii itafanya kwa kipande cha mwaka ujao kama 390 00:12:26,600 --> 00:12:28,570 kwa nini nilikuwa kubonyeza kwenye screen yangu mwenyewe. 391 00:12:28,570 --> 00:12:31,390 Lakini hebu tuangalie kwa haraka nini kilitokea mwaka jana 392 00:12:31,390 --> 00:12:34,770 na Jay, ambao walifika, sehemu kubwa kama Trevor hapa, alijitolea, 393 00:12:34,770 --> 00:12:39,380 na katika kipande cha hii fupi, utaona jinsi demo hiyo haikuweza 394 00:12:39,380 --> 00:12:41,074 yatangaza masomo sawa kujifunza. 395 00:12:41,074 --> 00:12:41,740 [VIDEO avspelning] 396 00:12:41,740 --> 00:12:45,360 -All Nataka kufanya sasa ni kupata kwa ajili yangu, na kwa ajili yetu, 397 00:12:45,360 --> 00:12:51,674 kweli, idadi 50 hatua moja kwa wakati. 398 00:12:51,674 --> 00:12:52,450 >> -The Idadi 50? 399 00:12:52,450 --> 00:12:53,190 >> -The Idadi 50. 400 00:12:53,190 --> 00:12:55,356 Na unaweza yatangaza nini nyuma ya kila moja ya milango hizi 401 00:12:55,356 --> 00:12:58,540 tu kwa kugusa kwa kidole. 402 00:12:58,540 --> 00:13:00,910 Damn it. 403 00:13:00,910 --> 00:13:02,870 >> [Akicheka] 404 00:13:02,870 --> 00:13:03,806 >> [Mwisho avspelning] 405 00:13:03,806 --> 00:13:05,430 DAVID J. Malan: Hivyo kwamba ilienda vizuri sana. 406 00:13:05,430 --> 00:13:06,796 Wale walikuwa milango zisizochambuliwa. 407 00:13:06,796 --> 00:13:08,670 Na Jay, bila shaka, kupatikana yote haraka haraka. 408 00:13:08,670 --> 00:13:12,910 Trevor alifanya kazi bora zaidi katika suala la wakati sikivu, 409 00:13:12,910 --> 00:13:15,850 hivyo kusema, mwaka huu katika kuchukua muda mrefu kupata hiyo. 410 00:13:15,850 --> 00:13:17,950 Bila shaka, basi sisi alitoa Jay nafasi ya pili, 411 00:13:17,950 --> 00:13:20,320 ambapo sisi yamepangwa milango, tu kama tulivyofanya kwa Trevor, 412 00:13:20,320 --> 00:13:22,300 na Trevor alifanya super vizuri wakati huu. 413 00:13:22,300 --> 00:13:26,124 Lakini Jay alifanya hivyo nusu kwa haraka. 414 00:13:26,124 --> 00:13:26,790 [VIDEO avspelning] 415 00:13:26,790 --> 00:13:29,650 Lengo -The sasa ni pia kupata yetu idadi 50, 416 00:13:29,650 --> 00:13:33,030 lakini kufanya hivyo algorithmically, na kutuambia jinsi gani wanaenda kuhusu hilo. 417 00:13:33,030 --> 00:13:33,660 >> -SAWA. 418 00:13:33,660 --> 00:13:35,604 >> -Na Kama wewe kupata hiyo, kuweka movie. 419 00:13:35,604 --> 00:13:37,228 Kama huna kupata hiyo, wewe kuwapa nyuma. 420 00:13:37,228 --> 00:13:38,044 >> -Man. 421 00:13:38,044 --> 00:13:38,860 >> -Oh! 422 00:13:38,860 --> 00:13:40,800 >> - [Inaudible] Sawa. 423 00:13:40,800 --> 00:13:46,236 Hivyo nina kwenda kuangalia ncha kwanza ili kuamua kama there's-- Oh. 424 00:13:46,236 --> 00:13:48,646 >> [Makofi] 425 00:13:48,646 --> 00:13:53,948 426 00:13:53,948 --> 00:13:55,729 >> [Mwisho avspelning] 427 00:13:55,729 --> 00:13:56,520 DAVID J. Malan: Sawa. 428 00:13:56,520 --> 00:13:59,760 Hivyo kuchagua milango wazi inaongoza kwa ufanisi mkubwa. 429 00:13:59,760 --> 00:14:01,680 Na hivyo, mara mbili kwa haraka ni nini mimi maana huko. 430 00:14:01,680 --> 00:14:03,270 Na hivyo Jay got bahati mara mbili. 431 00:14:03,270 --> 00:14:06,685 Naye pia alipata bahati kwa kuwa mwisho mwaka, mimi kuamuru baadhi rekodi Blu-ray 432 00:14:06,685 --> 00:14:07,560 kwa kweli kutoa nje. 433 00:14:07,560 --> 00:14:09,768 Nasikitika mwaka huu, sisi hawakuwa na huo, Trevor. 434 00:14:09,768 --> 00:14:11,540 Lakini bado bora ilikuwa miaka michache nyuma. 435 00:14:11,540 --> 00:14:14,820 Na baadhi yenu wanaweza kujua hii wenzake, Sean, ambaye alipokuwa katika CS50, 436 00:14:14,820 --> 00:14:17,780 ilikuwa changamoto kwa halisi tatizo moja, angalau katika SD, 437 00:14:17,780 --> 00:14:19,360 kama utasikia hivi karibuni kuona, nyuma katika siku. 438 00:14:19,360 --> 00:14:22,622 Na utapata kwamba si tu kwamba yeye kuchukua muda mrefu kidogo kuliko Jay, 439 00:14:22,622 --> 00:14:25,580 muda mrefu kidogo kuliko Trevor, ilikuwa kweli nafasi hii ya ajabu 440 00:14:25,580 --> 00:14:29,820 kujihusisha karibu kila mtu katika Umati la Bei ni Haki, na kuwahamasisha 441 00:14:29,820 --> 00:14:31,889 naye kupata idadi tulikuwa kutafuta. 442 00:14:31,889 --> 00:14:32,930 Hebu. tuangalie kwa haraka. 443 00:14:32,930 --> 00:14:33,320 >> [VIDEO avspelning] 444 00:14:33,320 --> 00:14:33,820 >> -SAWA. 445 00:14:33,820 --> 00:14:36,680 Hivyo kazi yako hapa, Sean, ni zifuatazo. 446 00:14:36,680 --> 00:14:40,860 I have siri nyuma hizi milango namba saba. 447 00:14:40,860 --> 00:14:45,120 Lakini zilizowekwa katika baadhi ya milango hizi pamoja ni idadi nyingine hasi. 448 00:14:45,120 --> 00:14:47,500 Na lengo ni kufikiri ya juu safu hii ya namba 449 00:14:47,500 --> 00:14:50,390 kama tu safu, au tu mlolongo wa vipande vya karatasi 450 00:14:50,390 --> 00:14:51,510 na namba nyuma yao. 451 00:14:51,510 --> 00:14:55,540 Na lengo ni, tu kutumia juu safu hapa, kupata mimi namba saba. 452 00:14:55,540 --> 00:14:58,570 Na sisi ni basi kwenda kukosoa jinsi ya kwenda juu ya kufanya hivyo. 453 00:14:58,570 --> 00:14:59,070 -Sawa. 454 00:14:59,070 --> 00:15:00,850 -Kupata Sisi namba saba, tafadhali. 455 00:15:00,850 --> 00:15:10,500 456 00:15:10,500 --> 00:15:11,000 Hakuna 457 00:15:11,000 --> 00:15:15,050 458 00:15:15,050 --> 00:15:18,550 Tano, 19, 13. 459 00:15:18,550 --> 00:15:22,240 460 00:15:22,240 --> 00:15:24,770 >> [Akicheka] 461 00:15:24,770 --> 00:15:25,910 >> Siyo suala hila. 462 00:15:25,910 --> 00:15:29,410 463 00:15:29,410 --> 00:15:29,910 Moja. 464 00:15:29,910 --> 00:15:33,218 465 00:15:33,218 --> 00:15:34,695 >> [Akicheka] 466 00:15:34,695 --> 00:15:37,861 Katika hatua hii, alama yako si sana nzuri, hivyo unaweza pia kuendelea. 467 00:15:37,861 --> 00:15:40,610 468 00:15:40,610 --> 00:15:41,110 Tatu. 469 00:15:41,110 --> 00:15:43,890 470 00:15:43,890 --> 00:15:45,378 >> [Akicheka] 471 00:15:45,378 --> 00:15:46,370 472 00:15:46,370 --> 00:15:47,774 >> Endelea. 473 00:15:47,774 --> 00:15:50,690 Kwa kweli, siwezi kusaidia lakini ajabu nini wewe hata kufikiria juu, so-- 474 00:15:50,690 --> 00:15:51,959 >> [Akicheka] 475 00:15:51,959 --> 00:15:53,229 476 00:15:53,229 --> 00:15:55,020 Tu safu ya juu, hivyo nimepata tatu kushoto. 477 00:15:55,020 --> 00:15:56,200 Hivyo kupata mimi saba. 478 00:15:56,200 --> 00:15:59,700 479 00:15:59,700 --> 00:16:02,167 >> [Akicheka] 480 00:16:02,167 --> 00:16:14,870 481 00:16:14,870 --> 00:16:15,370 17. 482 00:16:15,370 --> 00:16:25,675 483 00:16:25,675 --> 00:16:26,946 Saba. 484 00:16:26,946 --> 00:16:28,780 >> [Makofi] 485 00:16:28,780 --> 00:16:29,426 >> Sawa. 486 00:16:29,426 --> 00:16:30,360 >> [Mwisho avspelning] 487 00:16:30,360 --> 00:16:31,840 >> DAVID J. Malan: Hivyo tunaweza kuangalia hizi mchana kutwa. 488 00:16:31,840 --> 00:16:34,090 Na bila shaka, baadhi ya demos mwaka huu labda 489 00:16:34,090 --> 00:16:36,330 sasa kuishia katika kipindi cha video wa mwaka pia. 490 00:16:36,330 --> 00:16:39,040 Hivyo sasa hebu kweli kuzingatia algorithms 491 00:16:39,040 --> 00:16:42,140 hapa, na kuona kama hatuwezi sasa kuanza kurasimisha 492 00:16:42,140 --> 00:16:46,650 jinsi gani tunaweza kwenda juu ya kupata takwimu zetu ndani ya hali hii kwamba ni yamepangwa, 493 00:16:46,650 --> 00:16:50,054 ili hatimaye, tunaweza kweli kutafuta ni ufanisi zaidi. 494 00:16:50,054 --> 00:16:52,470 Na hata kama tunakwenda kutumia seti haki ndogo data, 495 00:16:52,470 --> 00:16:54,511 kama idadi nane sisi na hapa kwenye bodi, 496 00:16:54,511 --> 00:16:58,230 hatimaye mawazo haya hilo linaweza kuomba pembejeo 1,000, milioni pembejeo, 497 00:16:58,230 --> 00:17:02,100 Pembejeo bilioni 4, kwa sababu algorithms ni kwenda kuwa kimsingi huo. 498 00:17:02,100 --> 00:17:05,359 >> Na hivyo hii ni mwisho wetu fursa kwa watu wa kujitolea leo, 499 00:17:05,359 --> 00:17:09,790 lakini labda moja zaidi wanaohusika, kwa ambayo tunahitaji watu wa kujitolea nane 500 00:17:09,790 --> 00:17:12,960 kuja na kutembea kwetu kupitia mchakato wa kuchagua kile hivi karibuni 501 00:17:12,960 --> 00:17:15,212 kuwa juu ya haya muziki anasimama hapa. 502 00:17:15,212 --> 00:17:16,170 Napenda kuanza nyuma hapa. 503 00:17:16,170 --> 00:17:19,692 >> Hivyo moja katika kijani turquoise-- ni nini? 504 00:17:19,692 --> 00:17:21,130 Je, wewe ni kufanya? 505 00:17:21,130 --> 00:17:21,630 Mbili. 506 00:17:21,630 --> 00:17:23,069 Kuja juu chini. 507 00:17:23,069 --> 00:17:23,569 SAWA. 508 00:17:23,569 --> 00:17:24,420 Tatu. 509 00:17:24,420 --> 00:17:25,400 Nne. 510 00:17:25,400 --> 00:17:27,247 Hebu ME sawa, tano. 511 00:17:27,247 --> 00:17:28,830 Wewe ni kuteuliwa na rafiki yako. 512 00:17:28,830 --> 00:17:31,340 Sita, saba, na wanane. 513 00:17:31,340 --> 00:17:32,130 Kuja juu juu. 514 00:17:32,130 --> 00:17:32,630 Sawa. 515 00:17:32,630 --> 00:17:33,190 Asante sana. 516 00:17:33,190 --> 00:17:33,689 Kuja juu juu. 517 00:17:33,689 --> 00:17:34,790 Kuja juu juu. 518 00:17:34,790 --> 00:17:35,330 >> Sawa. 519 00:17:35,330 --> 00:17:38,890 Kwa hiyo kile tuna here-- na hii ni miongoni mwa watu zaidi Awkward, 520 00:17:38,890 --> 00:17:42,390 tangu hii itahitaji kwamba ucheshi mimi kwa kidogo tu cha muda. 521 00:17:42,390 --> 00:17:43,442 Nanyi mtakuwa namba moja. 522 00:17:43,442 --> 00:17:44,150 Jina lako ni nini? 523 00:17:44,150 --> 00:17:44,610 >> ANNAN: Annan. 524 00:17:44,610 --> 00:17:45,526 >> DAVID J. Malan: Annan. 525 00:17:45,526 --> 00:17:46,092 David. 526 00:17:46,092 --> 00:17:46,800 Jina lako ni nini? 527 00:17:46,800 --> 00:17:47,140 >> JOSEPH: Joseph. 528 00:17:47,140 --> 00:17:49,190 >> DAVID J. Malan: Joseph, wewe ni namba mbili. 529 00:17:49,190 --> 00:17:52,260 >> SERENA: Serena, namba tatu. 530 00:17:52,260 --> 00:17:53,722 Stefan, namba nne. 531 00:17:53,722 --> 00:17:54,430 CYNTHIA: Cynthia. 532 00:17:54,430 --> 00:17:57,548 DAVID J. Malan: Cynthia, namba tano. 533 00:17:57,548 --> 00:17:58,452 [Inaudible] 534 00:17:58,452 --> 00:17:59,618 DAVID J. Malan: [inaudible]. 535 00:17:59,618 --> 00:18:00,391 David, idadi sita. 536 00:18:00,391 --> 00:18:00,890 MATT: Mathayo. 537 00:18:00,890 --> 00:18:02,160 DAVID J. Malan: Mathayo namba saba. 538 00:18:02,160 --> 00:18:02,850 Na? 539 00:18:02,850 --> 00:18:03,210 >> WAVERLY: Waverly. 540 00:18:03,210 --> 00:18:04,470 >> DAVID J. Malan: Waverly, namba nane. 541 00:18:04,470 --> 00:18:04,970 Sawa. 542 00:18:04,970 --> 00:18:06,510 Kama could-- whoops. 543 00:18:06,510 --> 00:18:08,820 Kama wote, kama yako Changamoto ya kwanza, kuna 544 00:18:08,820 --> 00:18:10,820 ni nane muziki anasimama hapa inakabiliwa na watazamaji. 545 00:18:10,820 --> 00:18:14,200 Kama unaweza kuweka namba yako juu ya hizi muziki anasimama kwa namna 546 00:18:14,200 --> 00:18:16,560 kuwa wao kujipanga kwa idadi sawa kwenye ubao. 547 00:18:16,560 --> 00:18:19,560 Hivyo kufanya wenyewe kuangalia kama kwamba kwa kuweka namba yako juu ya hizi muziki 548 00:18:19,560 --> 00:18:21,960 anasimama hapa. 549 00:18:21,960 --> 00:18:25,980 Bora hadi sasa. 550 00:18:25,980 --> 00:18:26,600 >> Bora. 551 00:18:26,600 --> 00:18:26,890 SAWA. 552 00:18:26,890 --> 00:18:29,556 Hivyo sasa, tunakwenda kuuliza swali katika njia kadhaa tofauti. 553 00:18:29,556 --> 00:18:31,610 Ni jinsi gani sisi kwenda juu ya kuchagua folks hizi hapa? 554 00:18:31,610 --> 00:18:34,500 Kwa sababu tulikuwa na mbinu chache mapema, ambapo tulikuwa 555 00:18:34,500 --> 00:18:36,360 aina ya kufanya ndoo mbili tofauti. 556 00:18:36,360 --> 00:18:38,842 Na kisha tulikuwa ujumla piecing mambo pamoja. 557 00:18:38,842 --> 00:18:41,050 Mara tu tuliona namba mbili aliyokuwa nayo pamoja, 558 00:18:41,050 --> 00:18:41,975 sisi kuziweka pamoja. 559 00:18:41,975 --> 00:18:43,350 Barua mbili ambazo ni pamoja. 560 00:18:43,350 --> 00:18:45,058 >> Lakini hebu angalia kama sisi hawezi kurasimisha hii, 561 00:18:45,058 --> 00:18:48,044 ili tuweze hatimaye kuwa baadhi Pseudo-kificho wewe, 562 00:18:48,044 --> 00:18:49,710 na ambayo unaweza kutatua matatizo haya. 563 00:18:49,710 --> 00:18:51,870 Hivyo sasa, mimi nina kuangalia nje katika namba hizi hapa. 564 00:18:51,870 --> 00:18:55,030 Na mimi kuona rundo zima la makosa. 565 00:18:55,030 --> 00:18:57,750 Hatimaye, nataka moja juu ya kushoto na nane juu ya haki. 566 00:18:57,750 --> 00:19:00,650 >> Na hivyo mimi nina kuangalia hizi mbili, nne na mbili. 567 00:19:00,650 --> 00:19:02,930 Na tatizo ni nini, ni wazi? 568 00:19:02,930 --> 00:19:04,261 Naam. 569 00:19:04,261 --> 00:19:04,760 So. 570 00:19:04,760 --> 00:19:07,160 Mbili ni wazi huja kabla ya nne, hivyo unajua nini? 571 00:19:07,160 --> 00:19:10,210 Hebu kwanza kuchukua mbinu tamaa, kama wewe, kiasi kama tatizo 572 00:19:10,210 --> 00:19:13,790 kuweka one-- kama unakumbuka kutoka Standard Edition wa kuweka tatizo moja, 573 00:19:13,790 --> 00:19:16,820 ambapo mimi ndani ya nchi tu kutatua tatizo hiyo ni haki hapa mbele yangu 574 00:19:16,820 --> 00:19:17,690 na kuona ambapo inaongoza yangu. 575 00:19:17,690 --> 00:19:17,870 >> SAWA. 576 00:19:17,870 --> 00:19:20,161 Hivyo mbili na nne, napenda kwenda mbele na tu wabadilishane wewe miwili. 577 00:19:20,161 --> 00:19:22,400 Kama unaweza kimwili hoja wenyewe na karatasi yako, 578 00:19:22,400 --> 00:19:25,040 Mimi kuonekana kuwa na kujipatia orodha katika hali bora zaidi. 579 00:19:25,040 --> 00:19:26,330 >> Sasa, wao ni nzuri. 580 00:19:26,330 --> 00:19:28,480 Mimi nina kwenda kusonga mbele, nne na sita, inaonekana ni nzuri. 581 00:19:28,480 --> 00:19:29,110 Si tatizo. 582 00:19:29,110 --> 00:19:30,440 Sita na nane, sawa. 583 00:19:30,440 --> 00:19:31,860 Nane na moja, tatizo jingine. 584 00:19:31,860 --> 00:19:34,750 Kwa sababu kile kweli kuhusu nane na moja? 585 00:19:34,750 --> 00:19:36,990 Mtu hawezi kuja kabla nane, na hivyo tunapaswa kufanya nini? 586 00:19:36,990 --> 00:19:38,090 Hebu wabadilishane hizi mbili. 587 00:19:38,090 --> 00:19:39,316 Moja na nane. 588 00:19:39,316 --> 00:19:40,690 Na sasa, nina kwenda kuendelea. 589 00:19:40,690 --> 00:19:42,030 Mimi nina kwenda kuendelea kutafuta mbele. 590 00:19:42,030 --> 00:19:42,840 Na hebu angalia nini kinatokea. 591 00:19:42,840 --> 00:19:44,680 Nane na tatu, ya Bila shaka, nje ya utaratibu. 592 00:19:44,680 --> 00:19:45,815 Hebu wabadilishane. 593 00:19:45,815 --> 00:19:46,940 Nane na saba, bila shaka. 594 00:19:46,940 --> 00:19:47,481 Nje ya utaratibu. 595 00:19:47,481 --> 00:19:48,280 Hebu wabadilishane. 596 00:19:48,280 --> 00:19:49,940 Nane na tano, bila shaka, hebu wabadilishane. 597 00:19:49,940 --> 00:19:50,560 Sawa. 598 00:19:50,560 --> 00:19:51,880 Orodha ni Iliyopangwa. 599 00:19:51,880 --> 00:19:53,060 ndiyo? 600 00:19:53,060 --> 00:19:54,280 >> OK, ni wazi si. 601 00:19:54,280 --> 00:19:55,860 Lakini ni kidogo bora, haki? 602 00:19:55,860 --> 00:19:57,270 Kwa sababu ilani kile kilichotokea. 603 00:19:57,270 --> 00:20:01,749 Kila wakati sisi kazi wabadilishane, ndogo idadi aina ya percolated kwa njia hiyo, 604 00:20:01,749 --> 00:20:03,790 na idadi kubwa zaidi percolated njia hii, au tutaweza 605 00:20:03,790 --> 00:20:06,880 kuanza akisema bubbled kwa kushoto au bubbled na haki. 606 00:20:06,880 --> 00:20:10,080 >> Sasa, ni haitoshi, kwa sababu saa bora idadi wapate 607 00:20:10,080 --> 00:20:11,990 wamehamia doa moja mbele, au saa mbaya, 608 00:20:11,990 --> 00:20:13,880 idadi anaweza kuwa wakiongozwa doa moja zaidi. 609 00:20:13,880 --> 00:20:16,369 Hivyo unajua nini, aina hii ya kazi pretty vizuri hadi sasa. 610 00:20:16,369 --> 00:20:17,410 Napenda tu kujaribu tena. 611 00:20:17,410 --> 00:20:18,880 Mbili na nne, wao ni sawa. 612 00:20:18,880 --> 00:20:20,180 Nne na sita, wao uko sawa. 613 00:20:20,180 --> 00:20:21,790 Sita na moja, nje ya utaratibu. 614 00:20:21,790 --> 00:20:23,007 Basi hebu wabadilishane wewe miwili. 615 00:20:23,007 --> 00:20:25,840 Na sasa, taarifa tatizo la mapya ya kupata kidogo bora tena. 616 00:20:25,840 --> 00:20:27,006 Sita na tatu, nje ya utaratibu. 617 00:20:27,006 --> 00:20:28,100 Hebu wabadilishane wewe miwili. 618 00:20:28,100 --> 00:20:29,730 Sita na saba, wewe ni vizuri. 619 00:20:29,730 --> 00:20:32,230 Saba na tano, bila shaka, nje ya utaratibu. 620 00:20:32,230 --> 00:20:33,920 Saba na nane, katika utaratibu. 621 00:20:33,920 --> 00:20:36,470 Na sasa, mimi haja ya kufanya hili mara kwa mara chache zaidi. 622 00:20:36,470 --> 00:20:39,830 Na kwa kweli, nadhani kwa wenyewe labda ni mara ngapi maximally 623 00:20:39,830 --> 00:20:41,330 Huenda nina kutembea na kurudi? 624 00:20:41,330 --> 00:20:42,390 >> Tutaweza kuja nyuma na kwamba. 625 00:20:42,390 --> 00:20:43,700 Hivyo mbili na nne bado ni sawa. 626 00:20:43,700 --> 00:20:44,940 Nne na moja, nope. 627 00:20:44,940 --> 00:20:45,747 Hivyo, hebu wabadilishane. 628 00:20:45,747 --> 00:20:47,830 Na tena, taarifa kuibua moja ni aina ya bubbling 629 00:20:47,830 --> 00:20:49,163 kwa upande wa kushoto, ambapo ni lazima. 630 00:20:49,163 --> 00:20:50,010 Nne na mitatu wabadilishane. 631 00:20:50,010 --> 00:20:51,330 Nne na sita. 632 00:20:51,330 --> 00:20:53,100 Sita na tano wabadilishane. 633 00:20:53,100 --> 00:20:53,959 Sita na saba. 634 00:20:53,959 --> 00:20:55,000 Saba na nane ni nzuri. 635 00:20:55,000 --> 00:20:55,500 >> Nzuri. 636 00:20:55,500 --> 00:20:58,460 Sisi ni kupata bora zaidi. 637 00:20:58,460 --> 00:20:59,130 Basi hebu angalia. 638 00:20:59,130 --> 00:21:00,940 Sasa, tuna mbili na moja. 639 00:21:00,940 --> 00:21:02,520 Bila shaka, wabadilishane. 640 00:21:02,520 --> 00:21:07,520 Mbili na tatu, tatu na nne, nne na tano, sita na saba, saba na nane. 641 00:21:07,520 --> 00:21:08,020 Nzuri. 642 00:21:08,020 --> 00:21:08,730 Na unajua nini? 643 00:21:08,730 --> 00:21:11,190 Kwa sababu mimi alifanya badiliko moja pale, napenda kufanya moja sanity hundi. 644 00:21:11,190 --> 00:21:13,023 Hebu kwenda njia yote nyuma ya mwanzo. 645 00:21:13,023 --> 00:21:13,680 SAWA. 646 00:21:13,680 --> 00:21:14,750 Moja, two-- yup, kuona kitu gani? 647 00:21:14,750 --> 00:21:15,870 Kitu ilikuwa na makosa. 648 00:21:15,870 --> 00:21:18,420 Tatu, nne, tano, sita, saba, nane. 649 00:21:18,420 --> 00:21:21,920 Na katika kupitisha hii ya mwisho, ni wewe starehe na sasa zangu 650 00:21:21,920 --> 00:21:23,830 kwa madai ni yamepangwa? 651 00:21:23,830 --> 00:21:24,330 SAWA. 652 00:21:24,330 --> 00:21:25,880 Kuibua, hiyo ni kweli kabisa. 653 00:21:25,880 --> 00:21:28,410 Lakini functionally, nini Je, pia tu kutokea 654 00:21:28,410 --> 00:21:31,870 kwa kuwa ufaulu mwisho kwamba utapata kuthibitisha kwamba orodha hii ni kweli 655 00:21:31,870 --> 00:21:32,660 yamepangwa? 656 00:21:32,660 --> 00:21:34,477 >> Je, mimi kufanya au kufanya hii kupita jana? 657 00:21:34,477 --> 00:21:35,810 Watazamaji: Hakukuwa na mabadiliko. 658 00:21:35,810 --> 00:21:36,120 DAVID J. Malan: Samahani? 659 00:21:36,120 --> 00:21:37,070 Watazamaji: Hakuna mabadiliko. 660 00:21:37,070 --> 00:21:38,653 DAVID J. Malan: Hakukuwa na mabadiliko. 661 00:21:38,653 --> 00:21:41,947 Hivyo itakuwa kijinga ya mimi kufanya algorithm kwamba kimoja tena 662 00:21:41,947 --> 00:21:43,780 kama sikuwa kufanya lolote mabadiliko mara ya kwanza. 663 00:21:43,780 --> 00:21:45,160 Na hali haujabadilika. 664 00:21:45,160 --> 00:21:47,576 Hakika, mimi si kwenda kufanya mabadiliko yoyote mara ya pili. 665 00:21:47,576 --> 00:21:49,820 Na hivyo, ni salama sasa kusema, orodha ni Iliyopangwa. 666 00:21:49,820 --> 00:21:52,069 >> Na hakika, huu ni sasa kitu ambacho tutaweza ujumla 667 00:21:52,069 --> 00:21:56,900 wito Bubble aina, ambapo pairwise, wewe kusahihisha makosa tena, 668 00:21:56,900 --> 00:22:00,210 na tena, na tena, na wewe kuweka kwenda na kurudi, 669 00:22:00,210 --> 00:22:03,370 na na kurudi, mpaka kufanya hakuna swaps hizo, ambapo kiwango 670 00:22:03,370 --> 00:22:07,089 unaweza kuwa na uhakika, ndiyo, mimi kumaliza fixing wote wa makosa. 671 00:22:07,089 --> 00:22:08,630 Hebu upya na kujaribu mbinu nyingine. 672 00:22:08,630 --> 00:22:11,590 Kama nyie naweza kurudi nyuma katika Ili ungekuwa wakati iliyopita, 673 00:22:11,590 --> 00:22:13,780 ambayo inaonekana kama hii. 674 00:22:13,780 --> 00:22:17,640 Sasa, hebu kuchukua mbinu a zaidi kidogo kama kitabu mtihani, 675 00:22:17,640 --> 00:22:21,122 ambapo tulikuwa mara kwa mara kuchagua barua ya alfabeti 676 00:22:21,122 --> 00:22:22,830 kwamba sisi aina ya alitaka kukabiliana na ijayo. 677 00:22:22,830 --> 00:22:26,420 Labda ilikuwa barua juu, kama A, au chini Z. barua 678 00:22:26,420 --> 00:22:28,170 >> Hivyo kila mtu ni nyuma katika utaratibu huu. 679 00:22:28,170 --> 00:22:29,800 Na sasa napenda kufanya hivyo. 680 00:22:29,800 --> 00:22:34,880 Hebu angalia Najua nina nambari nane hapa. 681 00:22:34,880 --> 00:22:37,410 Mimi nina kwenda kwenda mbele na tu kwa makusudi kuchagua 682 00:22:37,410 --> 00:22:38,520 ndogo vipengele. 683 00:22:38,520 --> 00:22:38,760 Sawa? 684 00:22:38,760 --> 00:22:39,801 Hii inaonekana Intuitive sana. 685 00:22:39,801 --> 00:22:42,560 Mbona mimi kupata ndogo kipengele, kuiweka ambapo ni mali, 686 00:22:42,560 --> 00:22:45,280 kisha kupata ijayo ndogo kipengele, kuweka ni ambapo ni mali, na tu kurudia. 687 00:22:45,280 --> 00:22:46,820 >> Kwa sababu shirikishi, kwamba wanapaswa kufanya kazi pia. 688 00:22:46,820 --> 00:22:48,441 Hivyo nne, hiyo ni idadi pretty ndogo. 689 00:22:48,441 --> 00:22:49,940 Mimi nina kwenda kukumbuka ambapo hii ni. 690 00:22:49,940 --> 00:22:50,523 Hebu subiri kidogo. 691 00:22:50,523 --> 00:22:51,577 Mbili ni ndogo. 692 00:22:51,577 --> 00:22:53,910 Napenda sasa kumbuka kuwa walipo wawili ni, na kusahau kuhusu nne. 693 00:22:53,910 --> 00:22:55,050 Tutaweza kukabiliana na kwamba baadaye. 694 00:22:55,050 --> 00:22:56,460 Sita, mimi si nia. 695 00:22:56,460 --> 00:22:57,810 Nane, mimi si nia ya. 696 00:22:57,810 --> 00:22:59,780 Moja ni yangu mpya idadi ndogo. 697 00:22:59,780 --> 00:23:01,470 Hivyo nina kwenda kukumbuka ambapo moja ni. 698 00:23:01,470 --> 00:23:02,534 Tatu, si nia. 699 00:23:02,534 --> 00:23:03,450 Saba, si nia. 700 00:23:03,450 --> 00:23:04,530 Tano, si nia. 701 00:23:04,530 --> 00:23:07,390 >> Hivyo bila kuanguka mbali hatua ya mwaka huu, 702 00:23:07,390 --> 00:23:09,890 Mimi nina kwenda kunyakua idadi one-- na ilikuwa ni nini jina yako tena? 703 00:23:09,890 --> 00:23:10,150 >> ANNAN: Annan. 704 00:23:10,150 --> 00:23:11,220 >> DAVID J. Malan: Annan. 705 00:23:11,220 --> 00:23:13,540 Na kama unaweza kujiunga na mimi katika mwanzo wa orodha, 706 00:23:13,540 --> 00:23:14,870 hebu kuweka wewe ambapo ni mali. 707 00:23:14,870 --> 00:23:16,080 Unfortunately-- nini jina lako? 708 00:23:16,080 --> 00:23:16,650 >> STEFAN: Stefan. 709 00:23:16,650 --> 00:23:18,191 >> DAVID J. Malan: Stefan ni katika njia. 710 00:23:18,191 --> 00:23:23,490 Hivyo kabla Stefan kutatua huu tatizo, tunapaswa kufanya nini? 711 00:23:23,490 --> 00:23:25,412 Tufanye nini na Stefan? 712 00:23:25,412 --> 00:23:27,269 >> Watazamaji: [inaudible]. 713 00:23:27,269 --> 00:23:28,060 DAVID J. Malan: Sawa. 714 00:23:28,060 --> 00:23:28,850 Hivyo tunaweza kufanya hivyo. 715 00:23:28,850 --> 00:23:31,730 Tuliweza aina ya kuchukua Stefan na wake nne, na tu kuiweka katika kutofautiana 716 00:23:31,730 --> 00:23:33,530 na kushikilia yake kwa baadhi ya kiasi cha muda, 717 00:23:33,530 --> 00:23:35,220 hivyo kufanya chumba kwa namba moja. 718 00:23:35,220 --> 00:23:36,280 Na si kwamba mbaya. 719 00:23:36,280 --> 00:23:39,270 Mimi naweza kupendekeza, kwa nini sio sisi tu ya kuweka Stefan hapa? 720 00:23:39,270 --> 00:23:41,610 Kwa nini huenda hii ni ukiukwaji wa moja mawazo tulianza 721 00:23:41,610 --> 00:23:44,830 kuzungumza juu ya mara ya mwisho, wiki iliyopita? 722 00:23:44,830 --> 00:23:45,330 Yeah? 723 00:23:45,330 --> 00:23:45,740 >> Watazamaji: [inaudible]. 724 00:23:45,740 --> 00:23:46,860 >> DAVID J. Malan: Hakuna ripoti ajili yake. 725 00:23:46,860 --> 00:23:49,735 Kama unafikiri ya hili, kwa kweli, kama safu, hii ni kama hasi moja, 726 00:23:49,735 --> 00:23:52,900 hivyo hakuna kumbukumbu kwa kweli hapa ikiwa huyu ndiye kweli safu, 727 00:23:52,900 --> 00:23:55,090 kama sisi alitangaza wiki iliyopita katika hotuba. 728 00:23:55,090 --> 00:23:56,250 Kwa hiyo, hatupaswi kufanya hivyo. 729 00:23:56,250 --> 00:23:57,340 Tunaweza kuhifadhi katika kutofautiana. 730 00:23:57,340 --> 00:23:57,820 >> Au unajua nini? 731 00:23:57,820 --> 00:23:59,153 Nilisikia mtu mwingine kupendekeza hilo. 732 00:23:59,153 --> 00:24:01,020 Nini kingine unaweza kufanya na Stefan? 733 00:24:01,020 --> 00:24:03,770 Mbona sisi tu kumfukuza na kumtia juu ya mahali pale namba moja alikuwa. 734 00:24:03,770 --> 00:24:05,170 Hivyo kama unataka kwenda zaidi ya hapo. 735 00:24:05,170 --> 00:24:07,300 Na hakika, huu ni nzuri ufumbuzi. 736 00:24:07,300 --> 00:24:10,480 Sasa kwa upande mmoja, nimekuwa aina ya kufanywa tatizo mbaya. 737 00:24:10,480 --> 00:24:13,650 Nne ni sasa mbali mbali kutoka ambapo ni lazima. 738 00:24:13,650 --> 00:24:14,900 Ni lazima kuelekea nusu huu. 739 00:24:14,900 --> 00:24:16,100 >> Lakini unajua nini? 740 00:24:16,100 --> 00:24:17,630 Ambazo zingeweza bahati mbaya. 741 00:24:17,630 --> 00:24:18,822 Labda namba nane alikuwa hapa. 742 00:24:18,822 --> 00:24:20,530 Na hivyo, labda tunataka waliopata bahati, 743 00:24:20,530 --> 00:24:22,460 na kusukuma nane karibu na mwisho. 744 00:24:22,460 --> 00:24:24,710 Hivyo katika mwisho wa siku, ni aina ya yote wastani nje. 745 00:24:24,710 --> 00:24:26,085 Hatuna haja ya huduma ya juu ya nne. 746 00:24:26,085 --> 00:24:29,400 Wote mimi huduma ya juu hivi sasa ni kuchagua kipengele ndogo. 747 00:24:29,400 --> 00:24:32,030 >> Na sasa, nini mimi kwenda kwa kufanya ni kusahau namba moja 748 00:24:32,030 --> 00:24:35,160 kudumu, kwa sababu ninajua orodha nyuma yangu sasa yamepangwa. 749 00:24:35,160 --> 00:24:36,720 Hivyo orodha yangu hapo awali ilikuwa na ukubwa nane. 750 00:24:36,720 --> 00:24:37,720 Sasa, ni ya kawaida saba. 751 00:24:37,720 --> 00:24:40,340 Hivyo tatizo langu ni kupata ndogo, angalau kwa mstari. 752 00:24:40,340 --> 00:24:43,022 Hivyo sasa, mimi nina kwenda kuchagua sasa ndogo kipengele, mbili. 753 00:24:43,022 --> 00:24:46,520 Sita, nane, nne, tatu, saba, watano. 754 00:24:46,520 --> 00:24:47,770 Hiyo ilikuwa ni kipengele ndogo. 755 00:24:47,770 --> 00:24:49,416 Kwa hiyo kile ni mimi kwenda kufanya with-- nini ilikuwa jina yako tena? 756 00:24:49,416 --> 00:24:49,760 >> JOSEPH: Joseph. 757 00:24:49,760 --> 00:24:50,085 >> DAVID J. Malan: Joseph? 758 00:24:50,085 --> 00:24:52,000 Tunakwenda kuondoka Joseph katika mahali. 759 00:24:52,000 --> 00:24:54,842 Sasa, mimi nina kwenda kwa kujifanya kwamba hawa guys are-- vizuri, 760 00:24:54,842 --> 00:24:56,550 Najua kwamba hizi mbili tayari Iliyopangwa. 761 00:24:56,550 --> 00:24:58,424 Hebu sasa kuzingatia salio ya orodha. 762 00:24:58,424 --> 00:25:00,080 Sita ni ndogo sasa. 763 00:25:00,080 --> 00:25:01,190 Nane ni kubwa. 764 00:25:01,190 --> 00:25:02,970 Nne sasa ni ndogo sasa. 765 00:25:02,970 --> 00:25:04,762 Tatu sasa ni ndogo sasa. 766 00:25:04,762 --> 00:25:07,720 Na hivyo sasa, mimi nina kwenda kuchagua tatu, ambao is-- nini jina lako tena? 767 00:25:07,720 --> 00:25:08,190 SERENA: Serena. 768 00:25:08,190 --> 00:25:10,620 DAVID J. Malan: Serena, kama unaweza kunyakua namba yako na wabadilishane with-- 769 00:25:10,620 --> 00:25:11,550 KALSANG: Kalsang. 770 00:25:11,550 --> 00:25:12,940 DAVID J. Malan: Kalsang. 771 00:25:12,940 --> 00:25:15,220 Kuja nyuma, na tuko kwenda wabadilishane hizo mbili. 772 00:25:15,220 --> 00:25:17,360 Na sasa, hebu kuweka hii juu ya autopilot. 773 00:25:17,360 --> 00:25:21,589 Mimi nina kwenda na kuondoka kwa nyie kuchagua ijayo mambo madogo. 774 00:25:21,589 --> 00:25:22,380 Dun, Dun, Dun, Dun. 775 00:25:22,380 --> 00:25:24,560 Idadi nne, unapaswa kufanya nini? 776 00:25:24,560 --> 00:25:26,261 Bora. 777 00:25:26,261 --> 00:25:27,760 Sasa, mimi nina kwenda kufanya kupita mwingine. 778 00:25:27,760 --> 00:25:28,590 Dun, Dun, Dun, Dun. 779 00:25:28,590 --> 00:25:31,465 Mimi naona tano ni ijayo ndogo. 780 00:25:31,465 --> 00:25:32,840 Sasa, mimi nina kwenda kuchukua pasi mwingine. 781 00:25:32,840 --> 00:25:33,631 Dun, Dun, Dun, Dun. 782 00:25:33,631 --> 00:25:34,880 Sita ni ndogo. 783 00:25:34,880 --> 00:25:35,520 Nzuri. 784 00:25:35,520 --> 00:25:36,585 Saba ni ndogo. 785 00:25:36,585 --> 00:25:37,085 Hakuna mabadiliko. 786 00:25:37,085 --> 00:25:38,630 Nane ni ndogo. 787 00:25:38,630 --> 00:25:39,170 Kufanyika. 788 00:25:39,170 --> 00:25:43,900 >> Kwa hiyo kile tumekuwa tu kufanyika kwa iteratively kuchagua kipengele moja baada ya nyingine 789 00:25:43,900 --> 00:25:47,230 ni kutekeleza jambo ambalo tuko kwenda kurasimisha kama uteuzi aina. 790 00:25:47,230 --> 00:25:49,120 Na ni pengine hata rahisi kueleza, 791 00:25:49,120 --> 00:25:51,310 kwa kuwa literally wote wanataka kufanya ni kuweka tu 792 00:25:51,310 --> 00:25:54,700 kwenda na kurudi kupitia orodha kuchagua, karibu ndogo kipengele, 793 00:25:54,700 --> 00:25:55,720 mpaka wewe ni kosa. 794 00:25:55,720 --> 00:25:58,650 >> Hivyo ni rahisi hata, pengine shirikishi, kuliko ya mwisho. 795 00:25:58,650 --> 00:26:00,020 Hebu jaribu moja iliyopita moja. 796 00:26:00,020 --> 00:26:03,060 Kama wewe guys inaweza upya wenyewe katika nafasi zifuatazo 797 00:26:03,060 --> 00:26:08,600 mara moja ya mwisho, hebu angalia kama hatuwezi sasa kurasimisha mbinu nyingine moja. 798 00:26:08,600 --> 00:26:12,857 Kwa kweli, ingekuwa mtu huko nje kama kupendekeza 799 00:26:12,857 --> 00:26:14,440 jinsi mwingine tunaweza kwenda juu ya kufanya hii? 800 00:26:14,440 --> 00:26:17,439 Bila msukosuko nje buzzwords au aina majibu kwamba tayari anajulikana, 801 00:26:17,439 --> 00:26:19,689 tu intuitively, nini inaweza sisi? 802 00:26:19,689 --> 00:26:21,635 >> Watazamaji: [inaudible]. 803 00:26:21,635 --> 00:26:22,510 DAVID J. Malan: Yeah. 804 00:26:22,510 --> 00:26:24,620 Hivyo kuna baadhi Intuition kubwa huko. 805 00:26:24,620 --> 00:26:28,020 Mambo mema wanaonekana kutokea hivi sasa katika sayansi ya kompyuta wakati sisi kugawanya 806 00:26:28,020 --> 00:26:30,832 na kushinda tatizo la kugawa katika nusu na nusu na nusu. 807 00:26:30,832 --> 00:26:32,540 Na hivyo kweli kweli, sisi inaweza kuanza kufanya hivyo. 808 00:26:32,540 --> 00:26:35,754 Na kwa kweli, kwamba kinaendelea kuwa, tutaweza kuona, moja ya ufumbuzi bora yetu bado. 809 00:26:35,754 --> 00:26:37,420 Lakini hebu kuja nyuma na kwamba kabla ya muda mrefu. 810 00:26:37,420 --> 00:26:40,500 Kwa kweli, sisi ni kwenda kufanya kuwa kidogo baadaye wiki hii. 811 00:26:40,500 --> 00:26:42,180 Nini kingine inaweza tufanye nini ili kutatua hili? 812 00:26:42,180 --> 00:26:44,647 Hivyo kila mtu hapa ni katika inaonekana random utaratibu. 813 00:26:44,647 --> 00:26:45,230 Unajua nini? 814 00:26:45,230 --> 00:26:48,320 Badala ya kwenda na kurudi, na kurudi, na kurudi 815 00:26:48,320 --> 00:26:50,624 kila wakati, hii anahisi kama Mimi nina kufanya mengi ya kutembea. 816 00:26:50,624 --> 00:26:52,790 Mbona mimi tu kuanza saa mwanzo wa orodha, 817 00:26:52,790 --> 00:26:54,960 na tu ya kuweka nne ambapo ni mali? 818 00:26:54,960 --> 00:26:59,680 Hivyo basi mimi kudhani kwa muda kwamba orodha yangu ni tu kipengele hiki cha kwanza. 819 00:26:59,680 --> 00:27:04,937 Ni nne yamepangwa katika wakati huu katika muda, kama wote najali ni kila kitu hapa? 820 00:27:04,937 --> 00:27:06,520 Hii ni aina ya trivially kweli, haki? 821 00:27:06,520 --> 00:27:10,000 Kama orodha zenye namba moja, na kuwa namba nne ni wazi yamepangwa. 822 00:27:10,000 --> 00:27:13,070 >> Hivyo basi mimi tu inasema kuwa orodha hii ni Iliyopangwa. 823 00:27:13,070 --> 00:27:15,090 Lakini sasa mimi kuwa na mapumziko ya orodha hii. 824 00:27:15,090 --> 00:27:17,240 Hivyo sasa, mimi kukutana miwili. 825 00:27:17,240 --> 00:27:21,690 Wapi mbili ni wazi mali na heshima kwa nne? 826 00:27:21,690 --> 00:27:22,580 Kabla ya nne. 827 00:27:22,580 --> 00:27:23,862 Hivyo nini naweza kufanya hapa? 828 00:27:23,862 --> 00:27:24,820 Nini jina yako tena? 829 00:27:24,820 --> 00:27:25,090 >> JOSEPH: Joseph. 830 00:27:25,090 --> 00:27:26,030 >> DAVID J. Malan: Joseph, kama unaweza kurudi nyuma 831 00:27:26,030 --> 00:27:27,790 kwa muda tu na namba yako. 832 00:27:27,790 --> 00:27:31,130 Na sasa nini unapaswa Stefan kufanya hapa? 833 00:27:31,130 --> 00:27:33,720 Hebu kuhama Stefan zaidi ya hapa. 834 00:27:33,720 --> 00:27:35,520 Na sasa, basi Joseph kuja hapa. 835 00:27:35,520 --> 00:27:39,660 Na sasa, napenda kudai kwamba kila kitu hapa ni Iliyopangwa. 836 00:27:39,660 --> 00:27:42,474 Kwa hiyo, matokeo sawa, lakini a mbinu tofauti kimsingi. 837 00:27:42,474 --> 00:27:44,140 Mimi si hata inaonekana nini chini huko. 838 00:27:44,140 --> 00:27:46,310 I just kushika kuchukua mambo kama wao ni mitupu kwangu, 839 00:27:46,310 --> 00:27:47,240 na kukabiliana nao. 840 00:27:47,240 --> 00:27:48,330 >> Hivyo sasa, naona idadi sita. 841 00:27:48,330 --> 00:27:51,110 Wapi namba sita ni mali? 842 00:27:51,110 --> 00:27:53,250 Tuna mbili, nne, sita. 843 00:27:53,250 --> 00:27:54,800 Hasa ambapo yeye ni sasa hivi. 844 00:27:54,800 --> 00:27:57,750 Basi hebu kuondoka kwamba peke yake, na sasa kudai kwamba sehemu hii ya orodha 845 00:27:57,750 --> 00:27:58,772 sasa yamepangwa. 846 00:27:58,772 --> 00:28:01,230 Na hivyo, hii anahisi kimsingi tofauti kwa kuwa mimi nina tu 847 00:28:01,230 --> 00:28:05,230 kusonga kupitia orodha hapa mstari, na mimi nina kamwe mara dufu nyuma. 848 00:28:05,230 --> 00:28:05,730 Ndiyo. 849 00:28:05,730 --> 00:28:06,230 Sawa. 850 00:28:06,230 --> 00:28:08,190 Hivyo nane, wapi wewe ni mali? 851 00:28:08,190 --> 00:28:08,730 Hapa hapa. 852 00:28:08,730 --> 00:28:09,310 Kamilifu. 853 00:28:09,310 --> 00:28:10,210 Hivyo sasa, moja. 854 00:28:10,210 --> 00:28:10,900 Uh-oh. 855 00:28:10,900 --> 00:28:13,010 Hii anahisi kama ni kwenda kuwa ghali. 856 00:28:13,010 --> 00:28:15,690 Sasa, katika algorithm uliopita, I just walibadilishana watu. 857 00:28:15,690 --> 00:28:18,648 Hivyo mimi ili kumtia njia zote kwa mwanzo, lakini kisha kuhamia Joseph. 858 00:28:18,648 --> 00:28:21,450 Lakini kama mimi hoja Joseph, sasa nini kinaendelea kuwa makosa? 859 00:28:21,450 --> 00:28:24,250 >> Sasa, nimekuwa aina ya undone-- nimekuwa kuchukuliwa hatua moja mbele na kisha 860 00:28:24,250 --> 00:28:26,300 hatua moja nyuma, kwa sababu sasa Joseph itakuwa nje ya utaratibu. 861 00:28:26,300 --> 00:28:26,830 Basi hebu kufanya hivyo. 862 00:28:26,830 --> 00:28:29,150 Kama unaweza kuchukua namba moja na kurudi nyuma kwa muda tu. 863 00:28:29,150 --> 00:28:30,490 Je, tunawezaje put-- nini ilikuwa jina yako tena? 864 00:28:30,490 --> 00:28:31,130 >> ANNAN: Annan. 865 00:28:31,130 --> 00:28:32,610 >> DAVID J. Malan: Annan katika mahali? 866 00:28:32,610 --> 00:28:36,091 Nini mahitaji ya kutokea kwa heshima kwa mbili, nne, sita, na nane? 867 00:28:36,091 --> 00:28:37,570 Wote unahitaji kuhama. 868 00:28:37,570 --> 00:28:42,590 Hivyo kama nane wangependa kuhama kwanza, basi sita, basi nne, kisha mbili. 869 00:28:42,590 --> 00:28:45,380 Na kisha Annan, kama wewe d kama kuja hapa, nzuri. 870 00:28:45,380 --> 00:28:47,760 Lakini hapa, tumekuwa tu aina ya kulipwa bei 871 00:28:47,760 --> 00:28:49,510 katika hatua mbalimbali katika algorithm. 872 00:28:49,510 --> 00:28:52,550 Wakati mara ya mwisho kwa uteuzi aina, na hata Bubble aina, 873 00:28:52,550 --> 00:28:54,700 Mimi kutembea nyuma na nje, na kurudi, 874 00:28:54,700 --> 00:28:58,360 ambayo ni hakika kuongeza hadi muda-busara, na literally stepwise. 875 00:28:58,360 --> 00:29:00,660 >> Kuingizwa aina, kwa mara ya kwanza mtazamo, inaonekana kama ni 876 00:29:00,660 --> 00:29:05,150 super nadhifu, kwa kuwa Mimi tu kufanya polepole, Unaozidi maendeleo, 877 00:29:05,150 --> 00:29:07,120 lakini mimi si kwenda huu na kurudi. 878 00:29:07,120 --> 00:29:09,410 Lakini kama mtu ni kweli nje ya utaratibu, ilani 879 00:29:09,410 --> 00:29:10,840 yote ya kazi mimi tu alikuwa na kufanya. 880 00:29:10,840 --> 00:29:14,750 Mimi nilikuwa na hoja nusu ya orodha tu kufanya chumba kwa namba moja. 881 00:29:14,750 --> 00:29:16,790 Hivyo kiasi kama hicho ni ya kazi hivi sasa ni 882 00:29:16,790 --> 00:29:18,690 anahisi, tu aina mbalimbali za kazi. 883 00:29:18,690 --> 00:29:19,370 >> Hebu kuendelea. 884 00:29:19,370 --> 00:29:22,657 Hivyo sasa tunajua kwamba kila mtu kati ya moja na nane ni vyema. 885 00:29:22,657 --> 00:29:23,740 Hapa, nina namba tatu. 886 00:29:23,740 --> 00:29:25,864 Kama wewe kama kuchukua namba tatu, kurudi nyuma moja. 887 00:29:25,864 --> 00:29:28,260 Na je, guys haja ya kufanya? 888 00:29:28,260 --> 00:29:28,760 Yep. 889 00:29:28,760 --> 00:29:33,070 Hivyo hiyo ni mwingine moja, mbili, hatua tatu. 890 00:29:33,070 --> 00:29:36,010 Vitengo tatu wa wakati huo gharama tu mimi, ili tatu sasa wanaweza fit. 891 00:29:36,010 --> 00:29:37,460 Hatimaye, watu saba. 892 00:29:37,460 --> 00:29:39,730 >> Hebu kwenda mbele na kuwa na wewe kuchukua hatua nyuma. 893 00:29:39,730 --> 00:29:42,780 Hii ni tu kwenda gharama sisi kitengo moja ya muda, lakini hiyo ni sawa. 894 00:29:42,780 --> 00:29:44,170 Na sasa, tano ya kwenda kuwa ni kidogo ghali zaidi. 895 00:29:44,170 --> 00:29:45,340 Kama Ningependa kurudi nyuma. 896 00:29:45,340 --> 00:29:48,380 Tunahitaji kwenda nane, na saba, na sita. 897 00:29:48,380 --> 00:29:50,749 Na kisha kila mtu ni sasa yamepangwa. 898 00:29:50,749 --> 00:29:52,290 Hivyo upande kubwa kwa kujitolea yetu hapa. 899 00:29:52,290 --> 00:29:53,554 Asante sana. 900 00:29:53,554 --> 00:29:56,220 >> [Makofi] 901 00:29:56,220 --> 00:29:56,860 >> Asante wote. 902 00:29:56,860 --> 00:29:57,520 Asante wote. 903 00:29:57,520 --> 00:30:02,940 Basi hebu angalia sasa tu jinsi gharama kubwa zote za iliyokuwa. 904 00:30:02,940 --> 00:30:06,210 Hebu fikiria labda rahisi ya hizi, Bubble aina. 905 00:30:06,210 --> 00:30:09,950 Na mimi kusema rahisi, tu kwa sababu unaweza kutatua hayo kwa pupa na tu 906 00:30:09,950 --> 00:30:11,660 kurekebisha tatizo pairwise hapa. 907 00:30:11,660 --> 00:30:13,720 Kurekebisha tatizo pairwise hapa, tena na tena 908 00:30:13,720 --> 00:30:17,680 na tena, kurudia kama wengi mara kama wewe kweli haja ya. 909 00:30:17,680 --> 00:30:21,050 >> Hivyo zinageuka kuwa na aina Bubble, vizuri, 910 00:30:21,050 --> 00:30:25,820 jinsi hatua nyingi kufanya mimi kuchukua juu ya kupita kwanza ya kwamba algorithm? 911 00:30:25,820 --> 00:30:30,850 Nipate take-- hebu see-- moja, mbili, tatu, nne, tano, sita, saba. 912 00:30:30,850 --> 00:30:32,190 Na kuna mambo nane hapa. 913 00:30:32,190 --> 00:30:35,280 Hivyo ni kama n bala 1 hatua za kupata tangu mwanzo wa orodha 914 00:30:35,280 --> 00:30:36,380 hadi mwisho wa orodha. 915 00:30:36,380 --> 00:30:41,350 >> Lakini pamoja na uteuzi aina, kukumbuka kwamba mimi nina kuchagua mambo tena na tena 916 00:30:41,350 --> 00:30:44,590 na tena hiyo ni ndogo, Mimi nina kuweka katika nafasi, 917 00:30:44,590 --> 00:30:46,616 lakini kisha Mimi sio kuangalia nyuma yangu tena. 918 00:30:46,616 --> 00:30:49,490 Hivyo nadhani ni kidogo zaidi ya wazi basi hiyo mara ya kwanza, mimi ili 919 00:30:49,490 --> 00:30:52,680 Una kuchukua zote n bala 1 hatua kupata kipengele ndogo. 920 00:30:52,680 --> 00:30:55,920 Kisha mimi kuziweka katika nafasi, na mimi kumfukuza yeyote alikuwa hapa awali. 921 00:30:55,920 --> 00:30:57,500 >> Lakini basi sina kwa kuweka kuangalia kipengele hiki, 922 00:30:57,500 --> 00:30:59,040 kwa sababu najua ni Tayari ndogo. 923 00:30:59,040 --> 00:31:01,581 Hivyo sasa, siwezi kuangalia saba tu mambo, basi mambo sita, 924 00:31:01,581 --> 00:31:03,290 kisha mambo matano, basi mambo manne. 925 00:31:03,290 --> 00:31:06,900 Na hivyo hesabu, ikiwa n ni idadi ya vipengele au namba 926 00:31:06,900 --> 00:31:11,990 kwamba sisi ilianza na, unaweza kufikiria kwamba hii ni sawa na n bala 1, 927 00:31:11,990 --> 00:31:14,250 pamoja n bala 2 hatua, pamoja n bala hatua 3, 928 00:31:14,250 --> 00:31:16,780 pamoja n bala 4 hatua, kila njia ya chini kwa hatua moja tu. 929 00:31:16,780 --> 00:31:18,160 Na mimi nina juu ya mtu yangu ya mwisho. 930 00:31:18,160 --> 00:31:20,650 >> Na kama unakumbuka kwamba mengi ya stats vitabu au vitabu math 931 00:31:20,650 --> 00:31:24,730 na kanuni hizo juu Hardcover nyuma au mbele yao, 932 00:31:24,730 --> 00:31:27,690 zinageuka kuwa mfululizo huu inaweza kuwa walionyesha kwa urahisi zaidi 933 00:31:27,690 --> 00:31:28,857 kama mara n n bala 1 zaidi ya 2. 934 00:31:28,857 --> 00:31:31,273 Na ni faini kama si kwamba mstari wa mbele katika akili yako. 935 00:31:31,273 --> 00:31:32,420 Lakini huyu ndiye kweli kweli. 936 00:31:32,420 --> 00:31:34,449 Hiyo ni njia tu rahisi ya kuandika hayo. 937 00:31:34,449 --> 00:31:36,240 Na kisha kama unadhani nyuma ya shule ya daraja, 938 00:31:36,240 --> 00:31:38,698 wakati wewe tu kuanza kuzidisha mambo ya nje, hii bila shaka, 939 00:31:38,698 --> 00:31:41,820 ni tu n squared minus n kugawanywa na 2. 940 00:31:41,820 --> 00:31:44,772 Wote mimi tumefanya ni kupanua Maneno huko. 941 00:31:44,772 --> 00:31:46,730 Na hivyo hebu upya huu tofauti kidogo. 942 00:31:46,730 --> 00:31:49,780 Hiyo n squared kugawanywa na 2 minus n / 2. 943 00:31:49,780 --> 00:31:53,270 >> Hivyo tena, mimi nina aina tu ya kutumia baadhi hesabu sheria huko. 944 00:31:53,270 --> 00:31:57,140 Lakini taarifa sasa kwamba kubwa mrefu katika msemo huu, hivyo kusema, 945 00:31:57,140 --> 00:31:58,540 ni kwamba n squared. 946 00:31:58,540 --> 00:32:02,910 Hivyo ndiyo, ni n squared kugawanywa na 2, bala n / 2. 947 00:32:02,910 --> 00:32:05,080 >> Lakini kwa ujumla, ikiwa n ni kwenda kuwa thamani kubwa, 948 00:32:05,080 --> 00:32:08,740 Mimi nina kwenda kudai kwamba n squared ni kwenda kuwa sababu kubwa. 949 00:32:08,740 --> 00:32:10,490 Ni tu kwenda kuwa mchangiaji mkubwa 950 00:32:10,490 --> 00:32:12,877 kwa idadi ya hatua ya n / 2. 951 00:32:12,877 --> 00:32:13,960 Basi je, maana na hili? 952 00:32:13,960 --> 00:32:16,795 Hebu jaribu mfano rahisi, hata ingawa hesabu anapata kubwa kidogo. 953 00:32:16,795 --> 00:32:20,210 >> Hivyo tuseme tulikuwa watu milioni 1 juu ya hatua, au mambo milioni 1 954 00:32:20,210 --> 00:32:21,320 kwamba tunataka kutatua. 955 00:32:21,320 --> 00:32:23,730 Hebu kuziba milioni ndani ya hasa kwamba fomula 956 00:32:23,730 --> 00:32:27,230 kuona jinsi hatua nyingi inachukua jumla kutatua milioni mambo kwa kutumia kusema, 957 00:32:27,230 --> 00:32:28,560 uteuzi aina. 958 00:32:28,560 --> 00:32:30,760 >> Hivyo tunatarajia kuwa fomula sawa mbele. 959 00:32:30,760 --> 00:32:34,120 Ningependa kuziba milioni, ili niweze kupata milioni mraba kugawanywa na 2, 960 00:32:34,120 --> 00:32:35,990 bala milioni kugawanywa na 2. 961 00:32:35,990 --> 00:32:40,180 Kama mimi kufanya hivyo hesabu mapema hapa, tuna bilioni 500 962 00:32:40,180 --> 00:32:47,460 bala 500,000, ambayo inatupa 499,999,500,000, 963 00:32:47,460 --> 00:32:49,270 ambayo ni pretty darn kubwa. 964 00:32:49,270 --> 00:32:54,370 >> Kwa kweli, kama kulinganisha sasa 499,000,000,000, milioni 999, 965 00:32:54,370 --> 00:33:01,210 500,000 dhidi thamani yetu ya awali, Bilioni 500, ni hivyo damn karibu. 966 00:33:01,210 --> 00:33:06,850 Sawa? n squared kugawanywa na 2 huwapa us-- au tuseme, n squared kugawanywa na 2 967 00:33:06,850 --> 00:33:08,370 alitupa bilioni 500. 968 00:33:08,370 --> 00:33:13,510 Hiyo ni pretty darn karibu kwa 499,999,500,000, 969 00:33:13,510 --> 00:33:17,970 ambayo ni kusema subtracting mbali 500,000, au zaidi kwa ujumla, kutoa mbali 970 00:33:17,970 --> 00:33:20,010 n squared, si kweli mpango kubwa. 971 00:33:20,010 --> 00:33:22,490 N squared hufanya hivi nambari kukua kwa kweli kasi. 972 00:33:22,490 --> 00:33:25,790 >> Sasa, hii ni muhimu tu kadiri kama sisi, kama wanasayansi wa kompyuta, 973 00:33:25,790 --> 00:33:29,350 kwa ujumla hataenda kujali sana kuhusu nuances ya kanuni hizi 974 00:33:29,350 --> 00:33:31,400 na nini hasa majibu sahihi ni. 975 00:33:31,400 --> 00:33:33,390 Sisi matunzo tu kwamba, unajua nini? 976 00:33:33,390 --> 00:33:37,810 Mwisho wa siku, utaratibu huu ni juu ya utaratibu wa n squared. 977 00:33:37,810 --> 00:33:39,350 >> Ndiyo, sisi ni kugawa na 2 katika huko. 978 00:33:39,350 --> 00:33:41,360 Ndiyo, sisi ni subtracting mbali n bala 2. 979 00:33:41,360 --> 00:33:46,860 Lakini mwisho wa siku, mrefu kwamba kweli machungu yetu na gharama sisi 980 00:33:46,860 --> 00:33:48,995 mengi ya hatua ni kwamba mraba mrefu. 981 00:33:48,995 --> 00:33:51,370 Na hivyo kile kompyuta mwanasayansi kinaenda kwa ujumla kufanya 982 00:33:51,370 --> 00:33:54,160 ni kupuuza wale wote Ili suala ndogo, 983 00:33:54,160 --> 00:33:56,900 na tu kuangalia moja kwamba inachangia zaidi kwa gharama yoyote. 984 00:33:56,900 --> 00:34:00,530 >> Na hii ni nzuri, kwa sababu tunaweza sasa kuzungumza katika ujumla kubwa sana 985 00:34:00,530 --> 00:34:02,470 kuhusu algorithms, na unaweza kulinganisha yao. 986 00:34:02,470 --> 00:34:04,550 Na ukweli kwamba mimi nina kutumia O hii ni makusudi. 987 00:34:04,550 --> 00:34:06,680 Wakati mimi kusema juu ya utaratibu ya, mimi nina hasa 988 00:34:06,680 --> 00:34:09,560 akimaanisha kitu aitwaye kubwa O. Na kubwa O 989 00:34:09,560 --> 00:34:14,090 ni nukuu kwamba kompyuta Mwanasayansi anatumia kuelezea 990 00:34:14,090 --> 00:34:16,710 juu amefungwa juu ya kitu fulani. 991 00:34:16,710 --> 00:34:21,150 >> Hivyo kama wewe kusema kwamba algorithm ni katika kubwa O ya n squared, 992 00:34:21,150 --> 00:34:23,380 kama mimi mapendekezo tu wakati iliyopita, kwamba maana yake 993 00:34:23,380 --> 00:34:27,710 kwamba katika suala la mgombea wake muda au ufanisi wake, 994 00:34:27,710 --> 00:34:30,090 inachukua juu ya utaratibu ya n squared hatua. 995 00:34:30,090 --> 00:34:31,420 Labda zaidi, labda kidogo. 996 00:34:31,420 --> 00:34:33,435 Lakini ni juu ya utaratibu wa n squared. 997 00:34:33,435 --> 00:34:34,560 Na hiyo ndiyo amefungwa juu. 998 00:34:34,560 --> 00:34:36,530 Ni si kwenda kuwa chungu zaidi kuliko hiyo. 999 00:34:36,530 --> 00:34:40,800 Ni si kwenda kuwa n cubed, au 2 kwa n, au jambo kubwa sana. 1000 00:34:40,800 --> 00:34:43,800 Hii ni juu amefungwa juu ya gharama yoyote kwamba ni. 1001 00:34:43,800 --> 00:34:46,150 Hivyo kutokana na kwamba, hebu kufikiria mifano michache tu. 1002 00:34:46,150 --> 00:34:49,820 Na hii ni orodha mahususi ya kawaida sana mbio nyakati 1003 00:34:49,820 --> 00:34:52,870 kwa algorithms kwamba maana ya kuwa unaonyesha baadhi ya mambo tumekuwa 1004 00:34:52,870 --> 00:34:53,600 kuonekana tayari. 1005 00:34:53,600 --> 00:34:58,060 >> Hivyo kwa mfano, katika kesi ya uteuzi aina, nini mimi kudai hapa 1006 00:34:58,060 --> 00:35:02,250 ni kwamba uteuzi aina ya mbio muda ni juu ya utaratibu wa n squared. 1007 00:35:02,250 --> 00:35:06,260 Katika hali mbaya zaidi, mimi nina kwenda na rundo zima la idadi random hapa. 1008 00:35:06,260 --> 00:35:08,600 Na kama tuliona hesabu, kama mimi kuendelea kutembea 1009 00:35:08,600 --> 00:35:11,310 kupitia orodha, kupitia orodha, kuchagua ijayo ndogo 1010 00:35:11,310 --> 00:35:14,410 kipengele tena na tena, kama mimi kweli kuandika hatua zote 1011 00:35:14,410 --> 00:35:18,750 Mimi kuchukua kama mimi mapendekezo formulaically kabla, ni juu ya utaratibu wa n squared 1012 00:35:18,750 --> 00:35:20,370 hatua kwamba mimi nina kuchukua. 1013 00:35:20,370 --> 00:35:24,520 >> Na zinageuka kuwa Bubble aina na kuingizwa aina 1014 00:35:24,520 --> 00:35:27,370 ni kama mwepesi katika hali mbaya. 1015 00:35:27,370 --> 00:35:32,040 Fikiria, kwa mfano, kuingizwa aina, algorithm mwisho kabisa sisi kushughulikiwa, 1016 00:35:32,040 --> 00:35:35,500 ambayo ilikuwa na tuangalie kipengele, na kisha kuingiza ambapo ni mali. 1017 00:35:35,500 --> 00:35:38,720 Na kisha sisi inaonekana katika kipengele ijayo, na kuingizwa yake ambapo ni mali. 1018 00:35:38,720 --> 00:35:40,990 >> Hivyo kufikiria bora mazingira. 1019 00:35:40,990 --> 00:35:45,590 Tuseme nilikuwa kujitolea yangu kujipanga halisi kama hii, kwanza hadi la nane, 1020 00:35:45,590 --> 00:35:47,440 tayari Iliyopangwa. 1021 00:35:47,440 --> 00:35:51,300 Jinsi hatua nyingi ni kuingizwa aina kwenda kuchukua kutatua watu nane, 1022 00:35:51,300 --> 00:35:55,640 kama wao kufika katika jukwaa la kuangalia kama hii? 1023 00:35:55,640 --> 00:35:57,410 >> Watu nane tayari Iliyopangwa. 1024 00:35:57,410 --> 00:35:58,760 Na mimi kutumia kuingizwa aina. 1025 00:35:58,760 --> 00:36:02,180 Hiyo ya mwisho ya algorithms. 1026 00:36:02,180 --> 00:36:03,640 Naam, hebu kuigiza haraka kweli. 1027 00:36:03,640 --> 00:36:05,504 Hivyo kama mimi kuanza hapa, naona moja. 1028 00:36:05,504 --> 00:36:06,420 Ambapo gani mtu ni mali? 1029 00:36:06,420 --> 00:36:07,730 Iko hapa hapa. 1030 00:36:07,730 --> 00:36:08,330 Mimi naona mbili. 1031 00:36:08,330 --> 00:36:09,660 Wapi mbili ni mali? 1032 00:36:09,660 --> 00:36:10,260 Hapa hapa. 1033 00:36:10,260 --> 00:36:10,900 Mimi naona tatu. 1034 00:36:10,900 --> 00:36:11,920 Wapi tatu ni mali? 1035 00:36:11,920 --> 00:36:12,480 Hapa hapa. 1036 00:36:12,480 --> 00:36:13,100 >> Mimi naona nne. 1037 00:36:13,100 --> 00:36:13,600 Hapa hapa. 1038 00:36:13,600 --> 00:36:15,660 Tano, sita, saba, nane. 1039 00:36:15,660 --> 00:36:17,320 Hakuna sababu ya kurudia mwenyewe. 1040 00:36:17,320 --> 00:36:21,260 Na hatua hiyo, ni wangapi ni kwamba katika suala la n? 1041 00:36:21,260 --> 00:36:23,870 Ni juu ya utaratibu wa n hatua, sawa? n bala 1. 1042 00:36:23,870 --> 00:36:27,567 Lakini mimi alichukua idadi linear hatua, na sasa mimi nina kufanyika. 1043 00:36:27,567 --> 00:36:28,900 Hivyo hiyo ni kesi bora, ingawa. 1044 00:36:28,900 --> 00:36:29,983 Je kuhusu hali mbaya zaidi? 1045 00:36:29,983 --> 00:36:32,730 Nini nane walikuwa huko juu, na saba waliokuwa pale chini, 1046 00:36:32,730 --> 00:36:35,840 na moja na mbili zilikuwa zaidi ya hapa, hivyo kwamba orodha walikuwa kweli kuachwa? 1047 00:36:35,840 --> 00:36:38,300 >> Naam, nini kinatokea kweli kama hii ni idadi? 1048 00:36:38,300 --> 00:36:41,300 Na tutaweza kufanya michache tu ya mifano. 1049 00:36:41,300 --> 00:36:49,300 Nini kama, kwa hakika, idadi nane ni hapa, na whoops number--. 1050 00:36:49,300 --> 00:36:52,660 1051 00:36:52,660 --> 00:36:56,430 Basi nini kama, kwa hakika, idadi nane ni njia yote juu hapa, 1052 00:36:56,430 --> 00:36:57,790 na mimi nina kutumia kuingizwa aina? 1053 00:36:57,790 --> 00:36:58,290 >> SAWA. 1054 00:36:58,290 --> 00:37:00,280 Mimi kudai kwa sasa ni katika mahali. 1055 00:37:00,280 --> 00:37:03,152 Lakini sasa, seven-- wapi saba kwenda? 1056 00:37:03,152 --> 00:37:04,360 Bila shaka, unaendelea zaidi ya hapa. 1057 00:37:04,360 --> 00:37:06,760 Hivyo nina hoja nane juu ya sehemu moja. 1058 00:37:06,760 --> 00:37:08,554 Sasa sita, yanakwenda wapi? 1059 00:37:08,554 --> 00:37:09,220 Naam, haki zote. 1060 00:37:09,220 --> 00:37:13,150 Sasa, nina hoja nane juu ya mahali, na saba mahali, 1061 00:37:13,150 --> 00:37:14,440 na kisha mimi plop chini sita. 1062 00:37:14,440 --> 00:37:16,870 >> Hivyo mara ya kwanza, gharama mimi hatua moja ya kurekebisha mambo, 1063 00:37:16,870 --> 00:37:18,570 basi ni gharama mimi hatua mbili ili kurekebisha mambo. 1064 00:37:18,570 --> 00:37:20,370 Jinsi hatua nyingi ni kwenda kuchukua kurekebisha 1065 00:37:20,370 --> 00:37:22,720 mambo ya kuweka tano katika mahali sahihi? 1066 00:37:22,720 --> 00:37:23,340 Tatu. 1067 00:37:23,340 --> 00:37:29,520 Kwa sababu sasa nina hoja moja, mbili, tatu. 1068 00:37:29,520 --> 00:37:32,430 Jinsi hatua nyingi ni kwenda kuchukua kuweka nne katika mahali sahihi? 1069 00:37:32,430 --> 00:37:36,040 4 pamoja na 5, pamoja na 6, pamoja na 7. 1070 00:37:36,040 --> 00:37:40,260 >> Na hivyo ni hesabu kufanana na nini sisi kama ilivyoelezwa kwa uteuzi aina. 1071 00:37:40,260 --> 00:37:42,130 Tuna mfululizo huu hiyo ni kuongeza tu. 1072 00:37:42,130 --> 00:37:45,650 1 plus 2 pamoja na 3 pamoja na 4, au kinyume chake, 7 pamoja na 6 1073 00:37:45,650 --> 00:37:52,610 pamoja na 5 pamoja na 4 zinafikia kwa leo madhumuni ya juu ya utaratibu wa n squared. 1074 00:37:52,610 --> 00:37:57,640 >> Hivyo basi mimi inasema pia kwamba Bubble aina ni pia katika n squared. 1075 00:37:57,640 --> 00:38:01,340 Kwa sababu kwa Bubble aina, kila wakati mimi kwenda kupitia orodha, 1076 00:38:01,340 --> 00:38:03,100 Mimi kuchukua hatua takribani ngapi? 1077 00:38:03,100 --> 00:38:06,260 Kila wakati mimi literally kutembea kutoka huko kwa huko? 1078 00:38:06,260 --> 00:38:07,960 Takribani n hatua. 1079 00:38:07,960 --> 00:38:12,650 Lakini ni mara ngapi anaweza mimi haja ya kwenda kwa orodha? 1080 00:38:12,650 --> 00:38:13,920 >> Naam, takribani n huo. 1081 00:38:13,920 --> 00:38:15,680 Labda n bala 1, lakini takribani n mara. 1082 00:38:15,680 --> 00:38:16,430 Naam, kwa nini ni kwamba? 1083 00:38:16,430 --> 00:38:19,560 Naam, na Bubble aina, ikiwa sisi kuanza na aina Bubble, 1084 00:38:19,560 --> 00:38:23,570 na orodha katika mbaya iwezekanavyo hali hiyo, ambayo tena ni kabisa 1085 00:38:23,570 --> 00:38:25,550 nyuma, nini kitatokea? 1086 00:38:25,550 --> 00:38:28,830 Mimi kwenda kwa njia ya orodha, na idadi moja ni mali njia yote zaidi ya hapo. 1087 00:38:28,830 --> 00:38:33,280 >> Lakini pamoja na aina Bubble, jinsi mbali anafanya moja hoja juu ya kupita yangu ya kwanza kupitia orodha? 1088 00:38:33,280 --> 00:38:36,620 Jinsi maeneo mengi gani kupata karibu na mahali sahihi? 1089 00:38:36,620 --> 00:38:37,240 Moja tu. 1090 00:38:37,240 --> 00:38:40,281 Hivyo kama wewe aina ya sababu kwa njia hii, kila wakati kupitia algorithm hii, 1091 00:38:40,281 --> 00:38:41,880 Kuchukua takribani n hatua Daudi. 1092 00:38:41,880 --> 00:38:44,940 Lakini hupita wangapi kupitia orodha hiyo ni 1093 00:38:44,940 --> 00:38:49,060 kwenda kuchukua kwa moja kwa Bubble kwa upande wa kushoto ambapo ni mali? 1094 00:38:49,060 --> 00:38:51,840 >> Amepata hoja kama, nafasi n njia hii. 1095 00:38:51,840 --> 00:38:57,960 Hivyo tu kufanya kuchagua ya orodha, Nina kutembea na kurudi mara n. 1096 00:38:57,960 --> 00:39:01,540 Na kila wakati, mimi nina kuangalia n vipengele. 1097 00:39:01,540 --> 00:39:05,410 Hivyo kufanya mambo n mara n juu ya utaratibu wa n squared. 1098 00:39:05,410 --> 00:39:07,220 >> Sasa, tutaona katika baadhi ya kaptula kwamba 1099 00:39:07,220 --> 00:39:10,440 ni iliyoingia katika CS50 tatizo ijayo kuweka, mbinu nyingine katika hizo, 1100 00:39:10,440 --> 00:39:13,490 lakini kwa sasa, hebu tu kufikiria baadhi ya mbio Wakati mwingine, 1101 00:39:13,490 --> 00:39:16,840 hasa kama wale wa kuchagua kuchukua muda kidogo kuzama katika. 1102 00:39:16,840 --> 00:39:21,790 Nini algorithm tumeona tayari kwamba inachukua juu ya utaratibu wa hatua n? 1103 00:39:21,790 --> 00:39:27,560 >> Nini inapaswa kuchukua idadi linear ya hatua kwamba tumekuwa kuonekana hivi sasa? 1104 00:39:27,560 --> 00:39:29,350 Nini hiyo? 1105 00:39:29,350 --> 00:39:30,480 Search directory simu. 1106 00:39:30,480 --> 00:39:31,390 Algorithm kwanza. 1107 00:39:31,390 --> 00:39:31,560 Sawa? 1108 00:39:31,560 --> 00:39:33,650 Ambapo tuko mstari kwa ajili ya kutafuta Mike Smith? 1109 00:39:33,650 --> 00:39:34,150 Hakika. 1110 00:39:34,150 --> 00:39:37,180 Kutoka wiki sifuri, wakati mimi kuanza kugeuka ukurasa mmoja kwa wakati, 1111 00:39:37,180 --> 00:39:40,095 na mimi hata alisema kuwa ilikuwa ni aina ya linear hisia algorithm, 1112 00:39:40,095 --> 00:39:42,720 na tulikuwa na kwamba picha juu ya bodi na moja kwa moja line nyekundu 1113 00:39:42,720 --> 00:39:44,678 na njano sawa mstari, wale walikuwa kwa hakika 1114 00:39:44,678 --> 00:39:46,810 algorithms kwamba ni katika O kubwa ya n. 1115 00:39:46,810 --> 00:39:50,680 >> Kwa sababu kupata Mike Smith katika simu kitabu cha kurasa n, katika hali mbaya zaidi, 1116 00:39:50,680 --> 00:39:52,422 inaweza kuchukua yangu n hatua. 1117 00:39:52,422 --> 00:39:53,630 Nini juu ya kuchukua mahudhurio? 1118 00:39:53,630 --> 00:39:55,790 Moja, mbili, tatu, nne, tano, sita. 1119 00:39:55,790 --> 00:39:59,420 Nini wakati mbio za hii algorithm kwa ajili ya kuchukua mahudhurio? 1120 00:39:59,420 --> 00:40:03,070 Big O ya n, kwa sababu katika nadharia mimi kuwa na uhakika kila mtu katika chumba hicho. 1121 00:40:03,070 --> 00:40:05,861 >> Sasa kama kando, nini kuhusu optimization nyingine kutoka wiki sifuri? 1122 00:40:05,861 --> 00:40:08,117 Mbili, nne, sita, nane, 10, 12. 1123 00:40:08,117 --> 00:40:10,200 Mwanasayansi kompyuta ingekuwa kutambua, kusubiri dakika, 1124 00:40:10,200 --> 00:40:12,320 hiyo ni juu ya utaratibu wa n kugawanywa na hatua mbili. 1125 00:40:12,320 --> 00:40:12,820 Sawa? 1126 00:40:12,820 --> 00:40:14,444 Kwa sababu mimi nina kufanya watu wawili kwa wakati mmoja. 1127 00:40:14,444 --> 00:40:17,015 Lakini tunakwenda kupuuza wale ili suala ya chini, 1128 00:40:17,015 --> 00:40:19,140 na tunakwenda tu kwa kutupa kugawanya na 2, 1129 00:40:19,140 --> 00:40:21,830 na tu kusema, O kubwa ya n kwa kuwa algorithm pia. 1130 00:40:21,830 --> 00:40:22,760 >> Nini kuhusu hili? 1131 00:40:22,760 --> 00:40:26,170 Tutaweza ruka juu baadhi ya haya, lakini kile ilikuwa algorithm kwamba alikuwa logi ya n? 1132 00:40:26,170 --> 00:40:29,900 Hiyo alichukua takribani kuingia hatua n? 1133 00:40:29,900 --> 00:40:30,870 Kugawanya na kushinda. 1134 00:40:30,870 --> 00:40:31,369 Hasa. 1135 00:40:31,369 --> 00:40:33,900 Kama kitabu cha simu mfano katika wiki sifuri na mapema leo, 1136 00:40:33,900 --> 00:40:36,191 ambapo sisi kugawanywa tatizo tena na tena na tena. 1137 00:40:36,191 --> 00:40:39,070 Sisi akauchomoa juu ya bodi katika wiki sifuri kama ikiwa na kijani line, 1138 00:40:39,070 --> 00:40:41,460 na sisi alisema siku hiyo ilikuwa ni algorithm logarithmic. 1139 00:40:41,460 --> 00:40:44,970 >> Na hakika, idadi ya hatua hiyo inachukua kufanya kugawanya na kushinda, 1140 00:40:44,970 --> 00:40:48,610 au tafuta binary kama tutaweza kuanza kuiita, kama ilivyo katika kitabu cha simu, 1141 00:40:48,610 --> 00:40:50,680 ni juu ya utaratibu wa gogo na hatua. 1142 00:40:50,680 --> 00:40:52,470 Na hii ni kidogo ya moja weird. 1143 00:40:52,470 --> 00:40:54,910 >> Nini inachukua hatua moja, au zaidi hasa 1144 00:40:54,910 --> 00:40:56,240 idadi ya mara kwa mara ya hatua? 1145 00:40:56,240 --> 00:40:58,865 Labda ni wawili, labda ni tatu, lakini kompyuta mwanasayansi tu 1146 00:40:58,865 --> 00:41:01,423 simplifies kama O kubwa ya 1, baadhi idadi ya mara kwa mara ya hatua. 1147 00:41:01,423 --> 00:41:04,256 Nini kitu unaweza kufanya hivyo inachukua idadi ya mara kwa mara ya hatua? 1148 00:41:04,256 --> 00:41:08,030 1149 00:41:08,030 --> 00:41:10,930 >> Nini wakati mbio za kupiga makofi? 1150 00:41:10,930 --> 00:41:11,920 Mara kwa mara wakati. 1151 00:41:11,920 --> 00:41:12,420 Sawa? 1152 00:41:12,420 --> 00:41:15,490 Kama, nini wakati mbio za kufanya jambo lolote ambalo huchukua moja tu 1153 00:41:15,490 --> 00:41:18,570 operesheni, kama magazeti F Habari Duniani. 1154 00:41:18,570 --> 00:41:24,110 Ambazo zinaweza kuwa alisema kuwa wakati mara kwa mara, isipokuwa chini kona kesi na magazeti F, 1155 00:41:24,110 --> 00:41:28,260 nini huenda wakati mbio ya magazeti F kweli kuwa? 1156 00:41:28,260 --> 00:41:28,790 Na kwa nini? 1157 00:41:28,790 --> 00:41:30,550 N kupimia katika kesi hiyo ni nini? 1158 00:41:30,550 --> 00:41:32,251 >> Watazamaji: [inaudible]. 1159 00:41:32,251 --> 00:41:33,250 DAVID J. Malan: Hasa. 1160 00:41:33,250 --> 00:41:34,900 Idadi ya wahusika tunataka magazeti. 1161 00:41:34,900 --> 00:41:36,191 Hivyo ni sana mazingira-nyeti. 1162 00:41:36,191 --> 00:41:39,910 Leo, tumekuwa kulenga mengi juu ya herufi na namba hapa kwenye ubao. 1163 00:41:39,910 --> 00:41:43,540 Lakini inaweza pia kuwa wahusika katika kamba halisi. 1164 00:41:43,540 --> 00:41:46,420 Hivyo ni zamu nje kuna mwingine hatua ambayo itaanza kujali juu, 1165 00:41:46,420 --> 00:41:48,530 na kwamba kinyume ya kubwa O, hivyo kusema. 1166 00:41:48,530 --> 00:41:50,120 >> Hiyo ni nukuu omega. 1167 00:41:50,120 --> 00:41:53,380 Wakati kubwa O ina maana nini, juu amefungwa juu ya yako bomba? 1168 00:41:53,380 --> 00:41:55,580 Maximally, ni kiasi gani wakati Huenda jambo kuchukua? 1169 00:41:55,580 --> 00:41:59,250 Omega-- pole hii anaendelea kuja up-- ni kinyume cha hilo, 1170 00:41:59,250 --> 00:42:02,960 ambapo ni chini amefungwa juu ya kiasi cha muda kitu inaweza kuchukua. 1171 00:42:02,960 --> 00:42:10,480 >> So. Kwa mfano, nini algorithm kwamba inachukua hatua daima n squared? 1172 00:42:10,480 --> 00:42:15,600 Naam, moja ya algorithms tumeona leo, kwa kweli, inaweza kuwa kwamba pia. 1173 00:42:15,600 --> 00:42:16,720 Uteuzi aina. 1174 00:42:16,720 --> 00:42:18,270 Uteuzi aina pretty kijinga. 1175 00:42:18,270 --> 00:42:21,760 Hata kama pole algorithm, hata kama safu tayari Iliyopangwa, 1176 00:42:21,760 --> 00:42:24,150 uteuzi aina ni kwenda kuendelea kutembea kupitia orodha 1177 00:42:24,150 --> 00:42:28,907 kwa kuhakikisha ina ndogo kipengele tena na tena na tena. 1178 00:42:28,907 --> 00:42:31,740 Na hata kama wewe binadamu katika watazamaji kujua kwamba, kusubiri dakika, 1179 00:42:31,740 --> 00:42:33,948 wewe tayari kupita ndogo kipengele, kompyuta 1180 00:42:33,948 --> 00:42:37,300 hajui kwamba mpaka inaonekana njia zote orodha. 1181 00:42:37,300 --> 00:42:40,240 Vile vile, chini amefungwa kwamba inaweza pia kuwa imezingatia 1182 00:42:40,240 --> 00:42:42,000 inaweza kuwa na muda linear. 1183 00:42:42,000 --> 00:42:48,260 >> Muda kiasi gani gani kuchukua ili mambo aina n katika bora 1184 00:42:48,260 --> 00:42:52,420 kesi kwa kutumia kitu kama Bubble aina? 1185 00:42:52,420 --> 00:42:54,280 Tuseme orodha yako tayari Iliyopangwa. 1186 00:42:54,280 --> 00:42:56,696 Tulisema Bubble aina inachukua utaratibu wa n squared hatua. 1187 00:42:56,696 --> 00:42:59,640 Lakini nini kama ni tayari Iliyopangwa? 1188 00:42:59,640 --> 00:43:02,310 Nini kama wewe kutambua baada ya moja kupita kupitia safu 1189 00:43:02,310 --> 00:43:03,540 kwamba kiunda hakuna swaps? 1190 00:43:03,540 --> 00:43:05,970 Je, unahitaji kuendelea kufanya zaidi hupita? 1191 00:43:05,970 --> 00:43:06,470 >> Hakuna 1192 00:43:06,470 --> 00:43:10,340 Hivyo chini amefungwa juu ya Bubble aina inaweza kuwa alisema kuwa linear. 1193 00:43:10,340 --> 00:43:11,830 Omega wa n. 1194 00:43:11,830 --> 00:43:14,450 Na tunaweza kuangalia wengine wa haya vilevile. 1195 00:43:14,450 --> 00:43:17,990 Basi hebu tuangalie kwa haraka saa tu taswira hapa 1196 00:43:17,990 --> 00:43:20,790 kuona jinsi haya kutofautisha wenyewe. 1197 00:43:20,790 --> 00:43:24,592 Mimi nina kwenda chini hapa katika hii ukurasa hiyo inapatikana kwenye tovuti C50 wa, 1198 00:43:24,592 --> 00:43:27,550 lakini itakuwa maumivu ya kupata kazi, tangu inatumia teknolojia iitwayo 1199 00:43:27,550 --> 00:43:30,560 Applets Java, ambayo ni kiasi kikubwa haikubaliki siku hizi, 1200 00:43:30,560 --> 00:43:32,730 angalau kwa Chrome na wengine kadhaa. 1201 00:43:32,730 --> 00:43:37,070 >> Na napenda kwenda mbele na kasi hii up na kueleza nini kinaendelea. 1202 00:43:37,070 --> 00:43:40,840 Hii ni maandamano ya Bubble aina, algorithm kwanza tuliyoyaangalia. 1203 00:43:40,840 --> 00:43:43,950 Na ni taswira katika kwamba kila wa baa hizi inawakilisha idadi. 1204 00:43:43,950 --> 00:43:45,710 Kubwa bar, kubwa idadi. 1205 00:43:45,710 --> 00:43:47,520 Ndogo bar, ndogo idadi. 1206 00:43:47,520 --> 00:43:50,353 Na nini unaweza kuona kuibua, hata ingawa hii ni kwenda super haraka, 1207 00:43:50,353 --> 00:43:53,699 ni kwamba bar nyekundu ni kama mimi, kutembea na kurudi kutatua matatizo. 1208 00:43:53,699 --> 00:43:56,740 Unaweza kuona kwamba mambo makubwa ni kweli inayobubujika ili haki, 1209 00:43:56,740 --> 00:43:59,650 na mambo madogo ni inayobubujika wa kushoto. 1210 00:43:59,650 --> 00:44:01,870 Na chini hapa, kama sisi kweli kuangalia karibu zaidi, 1211 00:44:01,870 --> 00:44:04,330 sisi kweli unaweza kuhesabu idadi ya kulinganisha na swaps 1212 00:44:04,330 --> 00:44:05,350 kwamba walikuwa kuwa alifanya. 1213 00:44:05,350 --> 00:44:07,360 >> Lakini badala yake, hebu angalia katika algorithm pili 1214 00:44:07,360 --> 00:44:11,240 sisi inaonekana katika mapema na yetu kujitolea, uteuzi aina. 1215 00:44:11,240 --> 00:44:13,500 Kuibua, ina athari tofauti sana. 1216 00:44:13,500 --> 00:44:16,820 Lakini ni, tena, Intuitive sana, katika kwamba sisi kuendelea kuchagua ijayo ndogo 1217 00:44:16,820 --> 00:44:18,660 kipengele, na sisi got kidogo bahati. 1218 00:44:18,660 --> 00:44:20,110 Hiyo waliona kimsingi kwa kasi zaidi. 1219 00:44:20,110 --> 00:44:22,840 Lakini kama sisi mbio hii tena na tena na tena kwa kura ya pembejeo, 1220 00:44:22,840 --> 00:44:26,680 tunataka kuona kwamba ni kweli bado katika O kubwa ya n squared. 1221 00:44:26,680 --> 00:44:29,920 >> Hebu kufanya moja ya mwisho moja hapa, kuingizwa aina, 1222 00:44:29,920 --> 00:44:33,180 ambayo ilikuwa algorithm tatu sisi inaonekana katika, na wanakumbuka 1223 00:44:33,180 --> 00:44:36,700 kwamba hii moja inahusika na mambo kama atakutana nao, 1224 00:44:36,700 --> 00:44:39,290 lakini basi labda mabadiliko mambo juu ya kufanya chumba, 1225 00:44:39,290 --> 00:44:41,660 kuingiza mambo ambapo ni mali. 1226 00:44:41,660 --> 00:44:45,330 >> Na hii pia kuishia kutoa matokeo ya mwisho. Sasa yote matatu ya wale 1227 00:44:45,330 --> 00:44:46,490 waliona pretty kufunga. 1228 00:44:46,490 --> 00:44:48,740 Na hakika, mimi mbio yao katika kipande cha nzuri sana. 1229 00:44:48,740 --> 00:44:52,510 Lakini kimsingi, wao ni wote pretty kutisha, kwa kuwa waaminifu. 1230 00:44:52,510 --> 00:44:56,960 Wote wa algorithms hizi hivi sasa kwamba kukimbia katika O kubwa ya n squared 1231 00:44:56,960 --> 00:44:59,270 kuchukua kidogo kabisa ya muda wa kukimbia katika mwisho. 1232 00:44:59,270 --> 00:45:01,920 >> Na hakika, tunaweza kuona na kuhisi hii mwishowe 1233 00:45:01,920 --> 00:45:04,090 kama mimi kuvuta up demo hii tatu na ya mwisho. 1234 00:45:04,090 --> 00:45:05,840 Hii ni mwingine taswira ambayo inaenda 1235 00:45:05,840 --> 00:45:08,500 kuonyesha Bubble aina upande wa kushoto, uteuzi aina katikati, 1236 00:45:08,500 --> 00:45:13,410 na kitu, kama moja ya yetu mkono inaibua mapema alipendekeza, 1237 00:45:13,410 --> 00:45:15,020 kuunganisha aina juu ya haki. 1238 00:45:15,020 --> 00:45:16,937 Kugawanya na kushinda mkakati juu ya haki. 1239 00:45:16,937 --> 00:45:19,520 Na hiyo ndiyo, kwa kweli, ni nini tuko kwenda kuangalia juu ya Jumatano. 1240 00:45:19,520 --> 00:45:21,990 Lakini hebu wakati hizi kwa kukimbia katika sambamba. 1241 00:45:21,990 --> 00:45:26,765 Ni takribani idadi sawa ya vipengele, wote mbio kwa wakati mmoja. 1242 00:45:26,765 --> 00:45:30,940 1243 00:45:30,940 --> 00:45:34,440 Bubble aina vs uteuzi aina vs kuunganisha aina. 1244 00:45:34,440 --> 00:45:36,760 >> Sasa, wao ni wote kukimbia katika nadharia kwa wakati mmoja. 1245 00:45:36,760 --> 00:45:39,830 CPU ni mbio katika kasi hiyo hiyo, lakini wewe 1246 00:45:39,830 --> 00:45:44,014 Unaweza kuhisi jinsi boring huu ni haraka sana kwenda kuwa, 1247 00:45:44,014 --> 00:45:45,930 na tu jinsi ya kufunga wakati sisi kuingiza kidogo ya wiki 1248 00:45:45,930 --> 00:45:49,330 algorithms sifuri ya Unaweza sisi kasi ya mambo up. 1249 00:45:49,330 --> 00:45:51,760 >> Na sasa hebu kulinganisha hizi kwa namna moja iliyopita. 1250 00:45:51,760 --> 00:45:55,710 Mimi kwenda mbele na tovuti CS50, ambapo 1251 00:45:55,710 --> 00:45:59,020 tuna kiungo huu wa mwisho kwa leo, ambapo mtu kwenye mtandao 1252 00:45:59,020 --> 00:46:03,960 kindly kuweka pamoja video ambayo Ukamataji nini kuchagua mbalimbali 1253 00:46:03,960 --> 00:46:07,510 algorithms kuonekana kama. 1254 00:46:07,510 --> 00:46:09,577 Hii ni kuingizwa aina. 1255 00:46:09,577 --> 00:46:12,072 >> [Beeping] 1256 00:46:12,072 --> 00:46:13,070 1257 00:46:13,070 --> 00:46:16,850 >> Ambapo wewe ni kuomba mzunguko kulingana na urefu wa bar bar. 1258 00:46:16,850 --> 00:46:19,826 Hii ni Bubble aina. 1259 00:46:19,826 --> 00:46:21,822 >> [Warped beeping] 1260 00:46:21,822 --> 00:46:33,299 1261 00:46:33,299 --> 00:46:45,774 >> Kuja juu ijayo is-- kuja up ijayo is-- uteuzi aina, 1262 00:46:45,774 --> 00:46:48,820 ambapo mara ya pili, sisi ni kuchagua ijayo ndogo kipengele, 1263 00:46:48,820 --> 00:46:51,820 na tunaweza kuona ni kuongezeka kutoka kushoto kwenda kulia. 1264 00:46:51,820 --> 00:47:01,120 1265 00:47:01,120 --> 00:47:04,000 >> Kuunganisha aina, mshindi yetu hivi sasa leo. 1266 00:47:04,000 --> 00:47:09,659 1267 00:47:09,659 --> 00:47:12,450 Taarifa ni jinsi gani kugawa vitu ndani ya [inaudible] nusu na robo. 1268 00:47:12,450 --> 00:47:17,510 1269 00:47:17,510 --> 00:47:21,660 Gnome aina, ambayo sisi si kuongelea, na inajenga kuibua 1270 00:47:21,660 --> 00:47:24,450 na audally kidogo ya sura tofauti na sauti. 1271 00:47:24,450 --> 00:47:27,060 1272 00:47:27,060 --> 00:47:30,160 Kwenda na kurudi, kusafisha mambo up. 1273 00:47:30,160 --> 00:47:32,230 Pia kuangalia nje heapsort kwenye tovuti guy huu. 1274 00:47:32,230 --> 00:47:36,100 1275 00:47:36,100 --> 00:47:36,810 >> Na hiyo ni yake. 1276 00:47:36,810 --> 00:47:38,210 Tutaona wewe wakati ujao. 1277 00:47:38,210 --> 00:47:42,647 1278 00:47:42,647 --> 00:47:48,334 >> [WHOOSHING NA MUZIKI] 1279 00:47:48,334 --> 00:50:24,839