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Re:yiyiyi4321的解法详细说明,说的不太好,大家多试一些例子吧。

Posted by scrip at 2007-09-10 19:01:25 on Problem 1844
In Reply To:Re:yiyiyi4321的解法详细说明,说的不太好,大家多试一些例子吧。 Posted by:xiaoyuanwang at 2007-05-17 12:24:10
> 同意楼主的思想.因为我也是这么想的,也是这么做的.也是这么过的.
> 证明很简单啊.
> 比如说有个数N,sum是1-i的和.如果sum=N,那么就不用说了,如果sum>N;
> rest=sum-N,
> rest%2==1.那么就不能找到这样解,这点我想大家都了解.
> 当他是偶数的时候就一定存在解.
> 原因是如果rest/2<=i,那么就已经找到解了,就是1+...-rest/2+...i ,明白吧.
> 如果rest/2>i,那么rest=rest-i*2;
> 剩下的rest/2就一定会<=i-1的.
> 因为减去之后sum=1+....(i-1)-i了.
> 呵呵.总之就是看rest的奇偶问题了.
> 哎,总之就这样了.自己都绕糊涂了,
> 自己举几个例子就能发现规律.

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