[sum_{i=0}^{n-1} {(-1)^{i}C_n^{i} A_{n-i}} ]

Given a two-dimensional array of positive and negative integers, a sub-rectangle is any contiguous sub-array of size 1 x 1 or greater located within the whole a...

有n个点，代号分别为0到n-1,然后第i个点有di个相连点，与i 相连的点的XOR sum 为si，求所有的边。

Today, Wet Shark is given n integers. Using any of these integers no more than once, Wet Shark wants to get maximum possible even (divisible by 2) sum. Please, ...

有个1到n的一个全排列，告诉你第i个数和全部n个数相比的较小数是多少，和自己相比时为0，于是有个主对角线为0的矩阵，求原数列

因为奇偶相同的两个数之和一定是偶数，所以YES->sum是偶数。 sum是偶数，那么一定是偶数个奇数加上任意个偶数，偶数个奇数两两合并一下就变成了偶数，n个偶数一定可以通过n-1次替代变成1个数。因此sum是偶数->YES。...

按字典序输出所有在123..n之间插入'+','-',' '结果为0的表达式。.http://train.usaco.org/usacoprob2?a=jUh88pMwCSQ&S=zerosum/

Problem Description Phoenix is picking berries in his backyard. There are n shrubs, and each shrub has ai red berries and bi blue berries.

The cows don't use actual bowling balls when they go bowling. They each take a number (in the range 0..99), though, and line up in a standard bowling-pin-like t...

Jerry is caught by Tom. He was penned up in one room with a door, which only can be opened by its code. The code is the answer of the sum of the sequence of num...