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>> Rob BOWDEN: Hi, mimi nina Rob.

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Je, sisi kuajiri search binary?

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Hebu kujua.

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Hivyo, kumbuka kwamba hii tafuta tunakwenda
kutekeleza recursively.

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Unaweza pia kutekeleza search binary
iteratively, hivyo kama wewe alifanya hivyo,

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kwamba kikamilifu faini.

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>> Sasa kwanza, hebu kumbuka nini
vigezo search ni maana ya kuwa.

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Hapa, tunaona int thamani, ambayo ni
wanatakiwa kuwa thamani user ni

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ajili ya kutafuta.

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Tunaona maadili int safu, ambayo
ni safu ambayo tuko

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kwa ajili ya kutafuta thamani.

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Na tunaona int n, ambayo ni
urefu wa safu yetu.

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>> Sasa, jambo la kwanza kwanza.

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Sisi kuangalia ili kuona kama n sawa na 0, katika
kesi ambayo sisi kurudi uongo.

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Hiyo tu kusema kama tuna tupu
safu, thamani ni wazi si katika

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safu tupu, ili tuweze kurudi uongo.

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>> Sasa, sisi kweli unataka kufanya binary
search sehemu ya kutafuta binary.

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Kwa hiyo, tunataka kupata katikati
kipengele cha safu hii.

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Hapa, tunasema katikati ni sawa na n kugawanywa
na 2, tangu hiki katikati ni

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kwenda kuwa urefu wa
safu yetu kugawanywa na 2.

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Sasa tunakwenda kuangalia kuona kama
hiki katikati ni sawa na thamani sisi ni

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ajili ya kutafuta.

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Hivyo kama maadili katikati ni sawa na thamani, sisi
anaweza kurudi kweli tangu sisi kupatikana

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thamani katika safu yetu.

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>> Lakini kama hiyo ilikuwa si ya kweli, sasa
tunahitaji kufanya kujirudia

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hatua ya kutafuta binary.

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Sisi haja ya kutafuta ama
kushoto wa safu au kwa

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katikati ya safu.

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Hivyo hapa, tunasema kama maadili katikati ni
chini ya thamani, hiyo ina maana thamani kwamba

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ilikuwa kubwa zaidi kuliko katikati
wa safu.

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Hivyo thamani lazima na haki ya
hiki kwamba sisi tu inaonekana katika.

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>> Hivyo hapa, tunakwenda
kutafuta recursively.

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Na tutaangalia nini sisi ni kupita
hii katika pili.

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Lakini sisi ni kwenda kutafuta kwa
haki ya hiki katikati.

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Na katika kesi nyingine, hiyo ina maana kwamba
thamani ilikuwa chini ya katikati ya

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safu, na hivyo tunakwenda
kutafuta upande wa kushoto.

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Sasa, kushoto ni kwenda kuwa
kidogo rahisi kuangalia.

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Hivyo, tunaona hapa kwamba sisi ni recursively
wito search ambapo kwanza

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Hoja ni kwamba, tena, thamani
sisi ni kuangalia juu.

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Hoja ya pili ni kwenda kuwa
safu kwamba tulikuwa kutafuta juu.

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Na hiki mwisho sasa ni katikati.

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Kumbuka parameter mwisho ni int wetu
n, hivyo kwamba ni urefu wa safu yetu.

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>> Katika wito kujirudia kutafuta, sisi ni
sasa kusema kwamba urefu wa

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safu ni katikati.

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Hivyo, kama safu yetu ilikuwa ya ukubwa 20 na sisi
searched katika index 10, tangu katikati ni

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20 kugawanywa na 2, hiyo ina maana sisi ni
kupita 10 kama mpya

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urefu wa safu yetu.

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Kumbuka kwamba wakati una safu
urefu wa 10, hiyo ina maana halali

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mambo ni katika fahirisi 0 kupitia 9.

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Hivyo hii ni nini hasa tunataka
bayana safu yetu updated - upande wa kushoto

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safu kutoka hiki katikati.

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>> Kwa hiyo, kuangalia kwa haki ni
vigumu kidogo zaidi.

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Sasa kwanza, hebu fikiria urefu
ya safu na haki ya

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katikati hiki.

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Hivyo, kama safu yetu ilikuwa ya ukubwa n, kisha
safu mpya itakuwa ya ukubwa n minus

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minus katikati 1.

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Kwa hiyo, hebu fikiria ya n minus katikati.

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>> Tena, kama safu yalikuwa ya kipimo 20 na
sisi kugawanya na 2 kupata katikati,

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hivyo katikati ni 10, kisha n minus katikati
ni kwenda kutupa 10, hivyo 10

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mambo ya haki ya katikati.

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Lakini pia tuna minus hii
1, tangu sisi hawataki

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ni pamoja na katikati yenyewe.

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Hivyo n minus katikati minus 1 inatupa
jumla ya idadi ya mambo ya haki

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ya katikati index katika safu.

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>> Sasa hapa, kumbuka kwamba katikati
parameter ni maadili safu.

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Hivyo hapa, sisi ni kupita
updated maadili safu.

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Hii maadili pamoja na katikati plus 1 ni
kweli kusema recursively simu

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search, kupita katika safu mpya, ambapo
kwamba safu mpya kuanza katikati

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pamoja na moja ya maadili yetu ya awali safu.

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>> syntax mbadala kwa ajili ya kwamba, sasa
umeingia kuona kuyatumia, ni

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maadili Ampersand katikati pamoja na 1.

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Hivyo, kunyakua pepe ya katikati
pamoja na moja ya kipengele cha maadili.

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>> Sasa, ikiwa hawakuridhishwa
kubadilisha safu kama kwamba,

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inaweza pia kuwa kutekelezwa hii kwa kutumia
kujirudia msaidizi kazi, ambapo

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kwamba msaidizi kazi inachukua
hoja zaidi.

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Hivyo badala ya kuchukua tu thamani,
safu, na ukubwa wa safu,

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msaidizi kazi inaweza kuchukua zaidi
hoja, ikiwa ni pamoja na index chini

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kuwa wewe huduma ya juu katika safu
na index ya juu kwamba huduma

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kuhusu safu.

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>> Na hivyo kuweka wimbo wa wote chini
index na juu index, huna

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haja ya milele kurekebisha
maadili ya awali safu.

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Unaweza tu kuendelea
kutumia maadili safu.

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Lakini hapa, taarifa hatuna haja msaidizi
kazi kwa muda mrefu kama sisi ni

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tayari kurekebisha awali
maadili safu.

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Tuko tayari kupita katika
updated maadili.

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>> Sasa, hatuwezi search binary juu ya
safu kwamba ni zisizochambuliwa.

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Hivyo, hebu kupata hii namna.

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Sasa, taarifa aina hiyo ni miwili iliyopita
vigezo int maadili, ambayo ni

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safu kwamba sisi ni kuchagua, na int n,
ambayo ni urefu wa safu kwamba

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sisi ni kuchagua.

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Kwa hiyo, hapa tunataka kutekeleza
algorithm kuchagua

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kwamba ni o ya n mraba.

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Unaweza kuchagua Bubble aina, uteuzi
aina, au kuingizwa aina, au

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baadhi aina nyingine tuna si
kuonekana katika darasa.

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Lakini hapa, tunakwenda
kutumia uteuzi aina.

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>> Kwa hiyo, tunakwenda iterate
juu ya safu nzima.

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Naam, hapa tunaona kwamba sisi ni iterating
kutoka kwa 0 n minus 1.

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Kwa nini si njia yote hadi n?

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Naam, kama tumekuwa tayari yamepangwa kwanza
n minus 1 vipengele, kisha

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hiki mwisho sana kile ambacho ni lazima kuwa tayari
katika mahali sahihi, hivyo kuchagua juu ya

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safu nzima.

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>> Sasa, kumbuka jinsi uteuzi
aina kazi.

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Sisi ni kwenda juu ya safu nzima
kuangalia kwa thamani ya chini katika

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safu na fimbo kwamba
mwanzoni.

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Kisha sisi ni kwenda kwa kipindi chote
safu tena kuangalia kwa pili

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ndogo hiki, na fimbo kwamba
katika nafasi ya pili katika

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safu, na kadhalika.

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Hivyo, kwamba ni nini hii ni kufanya.

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>> Hapa, sisi ni kuona kwamba sisi ni
kuweka kiwango cha chini sasa

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thamani kwa i-th index.

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Kadhalika iteration kwanza, tunakwenda
kufikiria thamani ya chini kuwa

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mwanzo wa safu yetu.

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Basi, tunakwenda iterate juu ya
salio wa safu, kuangalia kwa

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kuona kama kuna mambo yoyote ndogo kuliko
moja kwamba sisi ni sasa

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kuzingatia kiwango cha chini.

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>> Hivyo hapa, maadili j plus moja - hiyo ni
kidogo kuliko kile sisi ni sasa

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kuzingatia kiwango cha chini.

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Kisha tunakwenda update nini
tunafikiri ni kiwango cha chini kwa

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index j plus 1.

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Hivyo, kufanya kuwa katika safu nzima,
na baada ya hii kwa kitanzi, kiwango cha chini

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lazima hiki kima cha chini kutoka
i-th nafasi katika safu.

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>> Mara baada ya sisi na kwamba, tunaweza kubadilishana
thamani ya chini ndani ya i-th nafasi

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katika safu.

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Hivyo hii ni kubadilishana ya kiwango.

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Sisi kuhifadhi katika thamani ya muda -
i-th thamani katika safu -

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kuweka katika i-th thamani katika safu
thamani kima cha chini ambayo ni huko,

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na kisha kuhifadhi nyuma katika ambapo
thamani ya sasa kima cha chini cha kutumika kuwa

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i-th thamani katika safu, hivyo
kwamba hatukuwa kupoteza yake.

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>> Kwa hiyo, ambayo inaendelea juu ya
iteration ijayo.

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Tutaweza kuanza kuangalia kwa pili
thamani ya chini na kuingiza kwamba katika

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pili ya msimamo.

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On iteration tatu, tutaweza kuangalia kwa
thamani ya tatu chini na kuingiza

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kwamba katika nafasi ya tatu, na hivyo
juu ya mpaka tuna safu sorted.

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Jina langu ni Rob, na hii
mara uteuzi aina.

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