摘要：传送门 题意：给定一颗n个结点的树，树上有m个结点有队伍，求存不存在一个点s，到所有m个队伍所在结点的距离相等，如果存在输出可能一个的s。 分析：假设存在s，那么可以改变树的顺序，使得s是所有队伍结点的祖先，此时s的所有祖先都是满足的s，令所有满足条件的s中里队伍结点最近的s为ms。dfs可以求得队 阅读全文

摘要：Computer HDU - 2196 A school bought the first computer some time ago(so this computer's id is 1). During the recent years the school bought N-1 new co 阅读全文

摘要：Terrorist’s destroy HDU - 4679 There is a city which is built like a tree.A terrorist wants to destroy the city's roads. But now he is alone, he can o 阅读全文

摘要：Roads in the North POJ - 2631 Building and maintaining roads among communities in the far North is an expensive business. With this in mind, the roads 阅读全文

摘要：Labyrinth POJ - 1383 The northern part of the Pyramid contains a very large and complicated labyrinth. The labyrinth is divided into square blocks, ea 阅读全文