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利用数学

Posted by 8013 at 2004-03-20 11:32:39 on Problem 1604
In Reply To:怎么加速啊,有什么更快的算法吗? Posted by:dexter at 2004-03-07 21:17:36

我记得没错的话，是求n!的最后一位非零的吧？记为f(n)
根据式子
                    n-1
   (5n)! =  (10^n)n! ∏(5i+1)(5i+2)(5i+3)(5i+4)/2
                     i=0

可证明  f(5n)≡(2^n)f(n) (mod10)就可以了

Followed by:

Re:利用数学 (187) dexter 2004-03-20 17:55:51
- Re:利用数学 (9) minnowlf 2004-05-28 21:25:04
- Re:利用数学 (0) sting0218 2008-04-06 15:10:44
  - Re:利用数学 (8) sting0218 2008-04-06 15:11:06
妙，啊 (0) 200593141 2007-10-01 17:51:51
Re:利用数学 (195) suikay 2009-03-11 12:53:34

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