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Re:只要(A-B)是偶数就可以 的说明

Posted by xtu845 at 2009-02-22 19:58:27 on Problem 1844
In Reply To:yiyiyi4321的解法说明 Posted by:level at 2006-08-06 21:15:40
A=1+2+3...+i;B为题目输入
(A-B)为偶数 
1+2+3+...+i 一定能表示这个偶数

先说这样一个事实 1,2,...,i这i个数一定能表示从1到(1+i)*i/2这些数
比如:1,2,3这三个数
1:1
2:2
3:1+2
4:1+3;
5:2+3;
6:1+2+3;

所以上面结论就显然了 

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