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Re:什么叫乘法逆元？我表示我只会用二分法进行等比数列求和做此题……

Posted by lydliyudong at 2011-06-17 13:12:30 on Problem 1845 and last updated at 2011-06-17 13:33:05
In Reply To:倒，不会乘法逆元，用土鳖方法搞这题，写了高精才过的表示压力巨大…… Posted by:xuhaoran510 at 2011-04-10 10:55:54

RT
1+p+p^2+……+p^c=

1° odd(c)=true
 原式=cal(p,c)={p^[(c+1)>>1)] +1} *cal(p,(c-1)>>1);
2° odd(c)=false
 原式=cal(p,c)={p^[(c+1)>>1)] +1} *cal(p,(c-1)>>1) +p^c;

原理：例如c=3  分成(1+p)+(p^2+p^3)提出p^2，二分递归。
         c=4  分成(1+p)+(p^2+p^3)+(p^4)，p^4单独计算。 

http://hi.baidu.com/lydrainbowcat/blog/item/7078dcfbdf43be0e6d22eb83.html

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