大意: 给定无向连通图, 定义两个点$s,t$个价值为切断一条边可以使$s,t$不连通的边数. 求最大价值. 显然只有桥会产生贡献. 先对边双连通分量缩点建树, 然后求直径即为答案. #include <iostream> #include <cstdio> #include <queue> #define REP(i,a,n) for(int i=a;i<=n;++i) #define pb push_back using namespace std; cons…

题意: 就是求桥最多的一条路 解析: 先求连通分量的个数 然后缩点建图  求直径即可 #include <bits/stdc++.h> #define mem(a, b) memset(a, b, sizeof(a)) using namespace std; , INF = 0x7fffffff; vector<]; ], lowlink[maxn<<], sccno[maxn<<], dfs_clock, scc_cnt, d[maxn<<], v…

E - We Need More Bosses CodeForces - 1000E Your friend is developing a computer game. He has already decided how the game world should look like - it should consist of nn locations connected by mm two-waypassages. The passages are designed in such a…

大意: 给定无向图, 每个点最多属于一个简单环, 多组询问, 求给定起点终点, 有多少条简单路径. 先缩环, 然后假设两点树上路径经过$cnt$个环, 那么答案就为$2^{cnt}$. 要注意缩环建树时要加单向边. #include <iostream> #include <algorithm> #include <cstdio> #include <queue> #define REP(i,a,n) for(int i=a;i<=n;++i) #de…

题意:给你n个点和m条边的无向图,问你如果多加一条边的话,那么这个图最少的桥是什么 解题思路:无向图缩点和树的直径,用并查集缩点: #include<iostream> #include<algorithm> #include<cstring> #include<cstdio> #include<cstring> #include<queue> using namespace std; ; ; struct Edge { int ne…

无向图缩块后,以n所在的块为根节点,dp找每块中的最大值. 对于每一个桥的答案为两块中的较小的最大值和较小的最大值加1 CRB and Graph Time Limit: 8000/4000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 113    Accepted Submission(s): 41 Problem Description A connected, undi…

做到这里以后,总算是觉得tarjan算法已经有点入门了. 这题的题意是,给出若干个点和若干条边连接他们,在这个无向图中,问至少增加多少条边可以使得这个图变成边双联通图(即任意两点间都有至少两条没有重复边的路径可以到达,可以经过同一个点.这个条件等价于每一条边都至少在一个环中). 方法:将无向图缩点以后,找出那些度为1的点的个数cnt,那么答案就是(cnt+1)/2.这么一看,好像就是缩点以后使它变成强连通图的意思?大概强连通图是有向图才有的名词吧.. 和有向图缩点类似,只要把if(!belong…

Your friend is developing a computer game. He has already decided how the game world should look like — it should consist of nn locations connected by mm two-way passages. The passages are designed in such a way that it should be possible to get from…

E. Cactus   A connected undirected graph is called a vertex cactus, if each vertex of this graph belongs to at most one simple cycle. A simple cycle in a undirected graph is a sequence of distinct vertices v1, v2, ..., vt (t > 2), such that for any i…

<题目链接> 题目大意:给定一个$n$个节点$m$条边的无向图,问你对任意两点,最多有多少条特殊边,特殊边指删除这条边后,这两个点不能够到达. 解题分析: 特殊变其实就是指割边,题意就是问你任意两点的路径之间,割边的最大数量.比较裸的题目,由边双连通和树的直径拼凑而成. 用边双连通缩完点之后,树形DP算出最长链即可. #include <bits/stdc++.h> using namespace std; template<typename T> inline voi…