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Problem Description　　Coach Pang is interested in Fibonacci numbers while Uncle Yang wants him to do some research on Spanning Tree. So Coach Pang decides to solve the following problem:　　Conside

问题描述　　A市有n个交通枢纽，其中1号和n号非常重要，为了加强运输能力，A市决定在1号到n号枢纽间修建一条地铁。　　地铁由很多段隧道组成，每段隧道连接两个交通枢纽。经过勘探，有m段隧道作为候选，两个交通枢纽之间最多只有一条候选的隧道，没有隧道两端连接着同一个交通枢纽。　　现在有n家隧道施工的公司，每段候选的隧道只能由一个公司施工，每家公司施工需要的天数一致。而每家公司最多只能修建一条

While exploring his many farms, Farmer John has discovered a number of amazing wormholes. A wormhole is very peculiar because it is a one-way path that delivers you to its destination at a time that i

DescriptionOne cow from each of N farms (1 ≤ N ≤ 1000) conveniently numbered 1..N is going to attend the big cow party to be held at farm #X (1 ≤X ≤ N). A total of M (1 ≤ M ≤ 100,000) unidirectional...

DescriptionBackground Hugo Heavy is happy. After the breakdown of the Cargolifter project he can now expand business. But he needs a clever man who tells him whether there really is a way from the

DescriptionBessie is out in the field and wants to get back to the barn to get as much sleep as possible before Farmer John wakes her for the morning milking. Bessie needs her beauty sleep, so she w

DescriptionFreddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on another stone. He plans to visit her, but since the water is dirty and full of

DescriptionAs you know, all the computers used for ACM contests must be identical, so the participants compete on equal terms. That is why all these computers are historically produced at the same fac...

DescriptionJohn is a Chief Executive Officer at a privately owned medium size company. The owner of the company has decided to make his son Scott a manager in the company. John fears that the owne

Problem DescriptionConsider a network G=(V,E) with source s and sink t. An s-t cut is a partition of nodes set V into two parts such that s and t belong to different parts. The cut set is the subset...

DescriptionYou are in charge of setting up the press room for the inaugural meeting of the United Nations Internet eXecutive (UNIX), which has an international mandate to make the free flow of infor

DescriptionOn a grid map there are n little men and n houses. In each unit time, every little man can move one unit step, either horizontally, or vertically, to an adjacent point. For each little ma

DescriptionCows are such finicky eaters. Each cow has a preference for certain foods and drinks, and she will consume no others.Farmer John has cooked fabulous meals for his cows, but he forgot

Problem DescriptionAs we all know, machine scheduling is a very classical problem in computer science and has been studied for a very long history. Scheduling problems differ widely in the nature of...

[题目链接]思路：\qquad根据题意，题目中的有向图为一棵树加上一条冗余边。一棵树的所有子节点入度均为1，根节点入度为0，因此可以分为以下两种情况：\qquad （1）图中存在入度为2的节点。因为根节点的入度为0，添加一条边，入度最多加1，因此入度为2的点一定是子节点，要删除的边一定是连向这个节点的边之一，根是入度为0的节点。此时考虑删掉每条连向该节点的边，对剩下的图从根节点拓扑排序，若没有环且能遍历到所有点，则枚举的边就是答案；\qquad（2）图中点的入度均为1，即从子节点向根节点连一条边。此

DescriptionEvery cow's dream is to become the most popular cow in the herd. In a herd of N (1 <= N <= 10,000) cows, you are given up to M (1 <= M <= 50,000) ordered pairs of the form (A, B) that tel

DescriptionA rooted tree is a well-known data structure in computer science and engineering. An example is shown below:In the figure, each node is labeled with an integer from {1, 2,...,16}.

DescriptionA rooted tree is a well-known data structure in computer science and engineering. An example is shown below:In the figure, each node is labeled with an integer from {1, 2,...,16}.

E. Cyclic ComponentsYou are given an undirected graph consisting of n vertices and m edges. Your task is to find the number of connected components which are cycles.Here are some definitions of gr...

N (1 ≤ N ≤ 100) cows, conveniently numbered 1..N, are participating in a programming contest. As we all know, some cows code better than others. Each cow has a certain constant skill rating that is un