At 04:22 AM 6/3/00 +0000, Secret Squirrel wrote:
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>Out of all possible N-bit numbers, how many have exactly M ones (M <= N) ?
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>(Yes, I am ashamed that I can't remember combinatorial logic, and that
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>I am too lazy to open a book, so spare me the BS.)
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> N
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>Is it ( ) / 2 ? [ (N * N-1 * ... * N-M+1) / 2 ]
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> M
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no, that fails for N=2, M=1.
as a matter of fact, start with M=1 (answer:N) and then M=N (answer:1) and
you should be able to reason it out from there. I'm too lazy to go get the
book too.
