摘要： This is a problem given in the Graduate Entrance Exam in 2018: Which of the following is NOT a topological order obtained from the given directed grap 阅读全文

摘要： The task of this problem is simple: insert a sequence of distinct positive integers into a hash table first. Then try to find another sequence of inte 阅读全文

摘要： A clique is a subset of vertices of an undirected graph such that every two distinct vertices in the clique are adjacent. A maximal clique is a clique 阅读全文

摘要： Problem Description You have won a collection of tickets on luxury cruisers. Each ticket can be used only once, but can be used in either direction be 阅读全文

摘要： 有一天，欧姆诺姆发现了一串长度为n的宝石串，上面有五颜六色的宝石。他决定摘取前面若干个宝石来做成一个漂亮的项链。 他对漂亮的项链是这样定义的，现在有一条项链S，当S=A+B+A+B+A+...+A+B+A的时候是漂亮的，这儿A，B是一些宝石串，“+”表示连接操作。S中有k+1个A和k个B组成。A和B 阅读全文

摘要： You are given a tree (a graph with n vertices and n - 1 edges in which it's possible to reach any vertex from any other vertex using only its edges). 阅读全文

摘要： One day, sailormoon girls are so delighted that they intend to research about palindromic strings. Operation contains two steps: First step: girls wil 阅读全文

摘要： 将N分为若干个不同整数的和，有多少种不同的划分方式，例如：n = 6，{6} {1,5} {2,4} {1,2,3}，共4种。由于数据较大，输出Mod 10^9 + 7的结果即可。 Input输入1个数N(1 <= N <= 50000)。Output输出划分的数量Mod 10^9 + 7。Samp 阅读全文

摘要： Given N integers, you are supposed to find the smallest positive integer that is NOT in the given list. Input Specification: Each input file contains 阅读全文

摘要： 有一棵以1为根的树，他有n个结点，用1到n编号。第i号点有一个值vi。 现在可以对树进行如下操作： 步骤1：在树中选一个连通块，这个连通块必须包含1这个结点。 步骤2：然后对这个连通块中所有结点的值加1或者减1。 问最少要经过几次操作才能把树中所有结点都变成0。 注意：步骤1与步骤2合在一起为一次操 阅读全文