摘要： http://poj.org/problem?id=1222http://poj.org/problem?id=1830http://poj.org/problem?id=1681http://poj.org/problem?id=1753http://poj.org/problem?id=3185这几个题目都类似，都可以使用高斯消元来求解一个模2的01方程组来解决。有时候需要枚举自由变元，有的是判断存不存在解POJ 1222EXTENDED LIGHTS OUT普通的问题。肯定有唯一解。肯定枚举第一行去做，也可以使用高斯消元。 1 /* **************************. 阅读全文

摘要： TreeTime Limit:5000MSMemory Limit:131072KTotal Submissions:2825Accepted:769DescriptionYou are given a tree withNnodes. The tree’s nodes are numbered 1 throughNand its edges are numbered 1 throughN− 1. Each edge is associated with a weight. Then you are to execute a series of instructions on the tree 阅读全文