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Priklad z prijmacek na magistra

asked 2015-06-15 22:07:45 +0100

anonymous user

Anonymous

updated 2015-06-21 00:37:34 +0100

anonymous user

Anonymous

Zdravim, netusim, jak tohle spocitat (jak se dojde k vysledku?). Poradite prosim?

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answered 2015-06-15 23:29:09 +0100

OndraS gravatar image

updated 2015-06-15 23:34:04 +0100

Princip inkluze a exkluze:
Vsech ctyrznakovych slov je 3^4.
Tech ktere vynechavaji A je 2^4.
Tech ktere vynechavaji B je 2^4.
Tech ktere vynechavaji A i B je 1^4.
Celkem 3^4 - 2 x 2^4+1^4=81-2*16+1=50.

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Diky. Jde to take spocitat primo bez pouziti inkluze-exkluze (predpokladam, ze to bude slozitejsi)?

vilestra ( 2015-06-16 13:05:31 +0100 )edit

No clovek by si mohl rozmyslet, kolik tam kterych pismen bude (asi 6 moznosti) a pak pro kazde takove urcene pocty spocitat, kolik je takovych kombinaci. Nevim, jestli je to primejsi, kazdopadne je to pracnejsi.
Nebo take clovek muze vypsat vsech 50 moznosti, to je hodne prime.
Co vlastne vadi na PIE?

OndraS ( 2015-06-16 13:59:45 +0100 )edit

Ok, fine. Na PIE mi nevadi vubec nic, je to hezka metoda. Chtel jsem jen vedet, jak se to pocita opacnym zpusobem.

vilestra ( 2015-06-16 22:40:24 +0100 )edit

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Asked: 2015-06-15 22:07:45 +0100

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Last updated: Jun 15 '15