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>> Rob: Hi, mimi nina Rob, na hebu decipher
Vigenere mpango.

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Kitu hivyo kwanza tunahitaji kufanya ni kufanya
uhakika user aliingia kile sisi inatarajiwa

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yao katika amri line.

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Hivyo kama argc ni si 2 hiyo ina maana ama
user hakuingia kamba sisi

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wanataka kutumia kama encrypting wetu
uzi, au wao

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aliingia mambo mengi mno.

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Na hatujui nini cha kufanya
na yale mambo mengine.

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>> Hivyo sisi kuwaambia yale wao
wanapaswa kuwa aliingia.

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Na sisi kurudi.

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Sasa, kuchukua kwamba argc ilikuwa 2, tunaweza
kuendelea na wengine wa mpango.

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>> Sisi Alias ​​jina la argv [1]

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ndani ya keyword kutofautiana.

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Ili sisi hawana
kutumia jina argv [1]

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katika mapumziko ya mpango huo.

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Na labda tutaweza kusahau kile
hiyo ina maana na kadhalika.

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Keyword ni jina gani nzuri.

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Na tutaweza mara moja kunyakua urefu
Keyword haki yetu hapa.

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>> OK, hivyo sasa tunataka kuangalia kwamba
keyword yetu ni kweli halali.

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keyword sisi kutumia encrypt masharti
lazima tu kuwa herufi

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wahusika.

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Kama mtumiaji aliingia mashirika yasiyo ya herufi
wahusika, tunapaswa kusema, keyword

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lazima iwe na tu kupitia
Z na kisha kurudi.

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Hivyo hii kwa kitanzi iterates juu ya yote
wahusika wa keyword yetu, kuangalia

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kwamba kama mtu yuko si herufi kisha
tunahitaji magazeti onyo hilo.

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>> Sasa, mara moja sisi kupata hatua hii, tunajua
kwamba kamba lazima kuwa sahihi.

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keyword lazima kuwa sahihi.

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Na sasa tunahitaji kupata ujumbe kutoka
user kwamba wanataka sisi kwa

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fumbo na kwamba maneno muhimu.

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Hivyo kupata ujumbe huo, tuna
kufanya wakati kitanzi kwamba kwenda

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kuendelea kupata kamba kutoka kwa mtumiaji
mpaka waingie kamba halali.

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>> Kuendelea, tunaona hapa variable hii,
int nun_letters_seen.

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Tutaweza kuona kwa nini tunahitaji
kwamba katika pili.

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Lakini hii kwa kitanzi ni kwenda iterate
kutoka i sawa na 0 kwa njia yote hadi i

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sawa na n, ambayo ina maana sisi ni iterating
juu ya wote iwezekanavyo

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wahusika katika ujumbe wetu.

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Kwa sababu tunataka fumbo yote ya
wahusika katika ujumbe wetu.

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Hivyo taarifa sisi kufanya kama (isalphamessage [I],
kwa sababu hatutaki encrypt

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wahusika kuwa ni si herufi.

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Kama kuna alama, nafasi,
au namba, hatufanyi

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wanataka fumbo hizo.

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>> Sasa, kudhani kuwa ni herufi,
sisi kwanza wanataka kufikiri nini sisi

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kweli wanataka fumbo
ujumbe kwa kutumia.

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Basi je, mimi maana na kwamba?

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>> Hebu kudhani kuwa maneno muhimu
user aliingia mara abc.

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Hiyo ni nini sisi ni kutumia kwa fumbo.

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Sasa, naively, tunafikiri kwamba maana yake ni kwamba
tunataka fumbo tabia ya kwanza

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wa ujumbe wetu na 0, tangu njia
kupokezana tabia kwa 0.

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>> Tunataka fumbo tabia ya pili
na 1, tabia tatu na 2,

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tabia ya nne kwa 0, tano
na 1, sita na 2, na kadhalika.

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Lakini kumbuka, kwamba tunataka ruka
nafasi na alama na namba.

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Hii ina maana kwamba kama mtumiaji iliingia
hujambo dunia kama ujumbe

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kwamba wanataka fumbo, basi
tunataka fumbo h na 0

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sambamba na a, e na 1,
l na 2, l na 0, o na 1.

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Tunataka ruka nafasi, encrypted
w na 2, o na 0, 1, 2, 0.

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Hivyo taarifa, kama sisi alikuwa skipped
nafasi, basi sisi ingekuwa encrypted

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w na 0 na kuishia na
sahihi kamba.

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>> OK, hii ni nini tunahitaji variable
num_letters_seen kwa.

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Kama sisi tu kwenda fumbo kwa kutumia
njia hii, ambayo haina ruka

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alama, nafasi, na idadi, basi sisi
inaweza tu kutumia variable i kama nini

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kwa index katika maneno yetu muhimu na.

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Tunahitaji kutumia num_letters_seen kuweka
wimbo wa mahali halisi katika

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maneno muhimu kwamba tunataka index.

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Hivyo hapa, kama keyword tuna, kama
num_letter_seen mod keyword_length, hivyo

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kwa nini tunahitaji Mod
na Keyword urefu?

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>> Vizuri, hello dunia ilikuwa mfano mzuri.

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Kama keyword mara abc, basi tunahitaji
kuendelea fumbo na kisha b

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kisha c, kisha wrap nyuma kote,
a, b, c,, b, c.

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Kwa hiyo, tunahitaji Mod na Keyword urefu
ili kufuta nyuma kote.

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>> Hivyo kama hii ni barua uppercase,
kisha tunataka fumbo na

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nafasi ya kwamba barua katika alfabeti,
ambayo sisi kupata na tu

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kutoa mapato nje ya mji mkuu A. Na
vile vile, kwa barua lowercase, sisi

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wanaweza kupata muhimu kwamba tunataka na
kutoa mapato nje lowercase a.

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Hivyo bila kujali kama barua
katika maneno muhimu ilikuwa mji mkuu wa au

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barua lowercase, tunakwenda
fumbo kwa kiasi hicho.

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>> Sasa kwamba tuna muhimu yetu, tunaona hapa,
kwamba kama ujumbe i ni uppercase

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tabia, kisha tunataka mahesabu ya
nafasi katika alfabeti ya kwamba

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tabia, kuongeza muhimu yetu kwa hiyo, kufuta nyuma
karibu ili kwamba kama sisi akaenda nyuma

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z sisi kurudi, b, c, na kadhalika.

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Kisha, mwisho, kuongeza nyuma kwenye mji mkuu wa A. Hivyo
sisi kuhama nyuma katika [? Kiwe]?

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mbalimbali ya wahusika hawa badala ya
nafasi numeric katika alfabeti

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ya wahusika hawa.

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>> Na sisi kufanya kitu kimoja kwa
kesi wahusika chini.

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Ila tunataka Ondoa nje lowercase
a na kuongeza kuwa nyuma katika

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mwisho, Herufi za chini.

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Taarifa kwamba num_letter_seen ni tu
incremented kama ujumbe i mara

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herufi.

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Hii ni jinsi gani sisi ruka nafasi, alama, na
idadi katika maneno yetu muhimu, tangu

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num_letter_seen ni nini sisi ni kutumia
kwa index katika keyword yetu.

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>> Hatimaye, katika mwisho, sasa ujumbe kwamba
i imekuwa encrypted, sisi

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magazeti ujumbe i.

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Na hiyo ni yake.

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Jina langu ni Rob.

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Na hii ni Vigenere.

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>> [Music kucheza]

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