xD

I think CF should add Chinese to languages, too

//My English is not good, so the translation may not be perfect, but I think that you can understand it. 1003 Revenge of Nim II //Let's call the one who first play X, the other one Y. Nim's game's room for Y's cheat is to move some piles of objects(not all of them), Is it guarantee that X will lose? Nim's game's requirement of X will lose is XORSUM(a[i])=0. Y's goal is to find a non-empty set which XORSUM(a[i])=0. Let's think the a[i] here a line which each bit is 0 or 1. All the numbers form a matrix. The operation of this matrix is XOR. If this matrix satisfies Rank-mat=Row-Num-mat, then its any subsets' XORSum is unique, and the non-empty subset's XORSUM is not zero, or the Rank of the matrix will be smaller than RowNum. What about Rank-mat<RowNum-Mat? Then for any subsets which satisfies Rank-Submat<RowNum-Subset, the other row can get through the XOR of some of the rows of the matrix. Then there will be an subset A that XORSum(a[i]|a[i] belongs to subset A)=0.

Complexity: O(maxb^3)|maxb=log(maxa), about 40. Degree of difficulty: 2.0/5