职务地址:id=2762">POJ 2762 先缩小点.进而推断网络拓扑结构是否每个号码1(排序我是想不出来这点的. .. ).由于假如有一层为2的话,那么从此之后这两个岔路的点就不可能从一点到还有一点的. 代码例如以下: #include <iostream> #include <string.h> #include <math.h> #include <queue> #include <algorithm> #include…

题目链接:http://poj.org/problem?id=2762 思路:首先当然是要缩点建新图,由于题目要求是从u->v或从v->u连通,显然是要求单连通了,也就是要求一条长链了,最后只需判断链长是否等于新图顶点个数即可,至于如何求一条链长,直接dfs即可,注意点就是dfs是要从入度为0的顶点开始. #include<iostream> #include<cstdio> #include<cstring> #include<algorithm&g…

题目链接:http://poj.org/problem?id=2762 题意是 有t组样例,n个点m条有向边,取任意两个点u和v,问u能不能到v 或者v能不能到u,要是可以就输出Yes,否则输出No.注意一点,条件是或者!所以不是判断双连通图的问题. 我一开始没看到'or'这个条件,所以直接tarjan判断是否只有一个强连通分量,果断WA. 所以需要给原图缩点,用tarjan把图变成一个有向无环图,要是只有一个scc,那就直接输出Yes.那接下来讨论多个scc,要是新图中有两个及以上的点的入度为…

http://poj.org/problem?id=2762 Going from u to v or from v to u? Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 12733   Accepted: 3286 Description In order to make their sons brave, Jiajia and Wind take them to a big cave. The cave has…

题目链接:http://poj.org/problem?id=2762 题意:给出一个有向图,判断任意的两个顶点(u,v)能否从u到达v,或v到达u,即单连通,输出Yes或No. 分析:对于同一个强连通分量而言,所有的点都是互达的,如果该有向图只有一个强连通分量,则肯定是Yes了: 若有多个强连通分量呢?判断两个不同的强连通分量的点u和v是否单连通,缩点后,建新图,用拓扑排序判断,删除点的时候若发现有大于2个点的入度为0,则u和v必定不能连通. AC代码: #include<cstdio> #…

http://poj.org/problem?id=2762 题意:给出有向图,判断任意两个点u和v,是否可以从u到v或者从v到u. 思路: 判断图是否是单连通的. 首先来一遍强连通缩点,重新建立新图,接下来我们在新图中找入度为0的点,入度为0的点只能有1个,如果有多个那么这些个点肯定是不能相互到达的. 如果只有一个入度为0的点,走一遍dfs判断新图是否是单链,如果有分支,那么分支上的点肯定是不能相互到达的. #include<iostream> #include<algorithm&g…

题目链接: http://poj.org/problem?id=2762 Going from u to v or from v to u? Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 14546   Accepted: 3837 Description In order to make their sons brave, Jiajia and Wind take them to a big cave. The cav…

id=2762">http://poj.org/problem?id=2762 Going from u to v or from v to u? Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 14573   Accepted: 3849 Description In order to make their sons brave, Jiajia and Wind take them to a big cave. T…

Going from u to v or from v to u? Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 17089   Accepted: 4590 Description In order to make their sons brave, Jiajia and Wind take them to a big cave. The cave has n rooms, and one-way corridors…

Going from u to v or from v to u? Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 15494   Accepted: 4100 Description In order to make their sons brave, Jiajia and Wind take them to a big cave. The cave has n rooms, and one-way corridors…