ACM_10000h的专栏

This would mean that whenever a friend A dislikes a friend B, friend A must receive the invitation before B. Define "A must come before B" as a requirement: "B requires A" meaning that if we want to invite B, we must invite A first.

http://poj.org/problem?id=2513 题意： 给你很多对单词，单词相当于一个点，一对单词相当于一条边，问这么多对的单词能否组成一条欧拉路，要求每条边都要经过。 解析： 题目数据很大，每个单词最多10个字母，据说用map映射会TLE。  所有要改用字典树进行hash。  判断欧拉路径或者回路需要满足两个条件。  图上所有点联通  度数为奇数个的节点