poj3177 tarjan双联通缩点
来源:互联网 发布:商业银行网络金融联盟 编辑:程序博客网 时间:2024/05/16 06:28
In order to get from one of the F (1 <= F <= 5,000) grazing fields (which are numbered 1..F) to another field, Bessie and the rest of the herd are forced to cross near the Tree of Rotten Apples. The cows are now tired of often being forced to take a particular path and want to build some new paths so that they will always have a choice of at least two separate routes between any pair of fields. They currently have at least one route between each pair of fields and want to have at least two. Of course, they can only travel on Official Paths when they move from one field to another.
Given a descri_ption of the current set of R (F-1 <= R <= 10,000) paths that each connect exactly two different fields, determine the minimum number of new paths (each of which connects exactly two fields) that must be built so that there are at least two separate routes between any pair of fields. Routes are considered separate if they use none of the same paths, even if they visit the same intermediate field along the way.
There might already be more than one paths between the same pair of fields, and you may also build a new path that connects the same fields as some other path.
Input
Line 1: Two space-separated integers: F and R
Lines 2..R+1: Each line contains two space-separated integers which are the fields at the endpoints of some path.
Output
Line 1: A single integer that is the number of new paths that must be built.
Sample Input
7 7
1 2
2 3
3 4
2 5
4 5
5 6
5 7
Sample Output
2
Hint
Explanation of the sample:
- One visualization of the paths is: 1 2 3 +—+—+ | | | | 6 +—+—+ 4 / 5 / / 7 +Building new paths from 1 to 6 and from 4 to 7 satisfies the conditions. 1 2 3 +—+—+
- | |
- | |
6 +—+—+ 4
/ 5 :
/ :
/ :
7 + - - - -
Check some of the routes:
1 – 2: 1 –> 2 and 1 –> 6 –> 5 –> 2
1 – 4: 1 –> 2 –> 3 –> 4 and 1 –> 6 –> 5 –> 4
3 – 7: 3 –> 4 –> 7 and 3 –> 2 –> 5 –> 7
Every pair of fields is, in fact, connected by two routes.
It’s possible that adding some other path will also solve the problem (like one from 6 to 7). Adding two paths, however, is the minimum.
要求至少加几条边才能使这个图连通的无向图双联通
其实关键在于先缩点,然后建立新的图再说其他的….
缩点和强连通分量一样的用栈缩点就可以…
然后建立新的图就是一颗树
因为这是个连通图所以只有一棵树
一半的叶子结点+1可以得出答案
#include<iostream>#include<cmath>#include<vector>#include<algorithm>#include<cstdio>#include<cstring>#include<stack>using namespace std;vector<int>tu[5001];vector<int>xt[5001];int dfn[5001],low[5001],clj,jc,die[5001],sd[5001];bool mmm[5001][5001],ppp[5001][5001];stack<int>ss;void tarjan(int dian,int ba){ dfn[dian]=low[dian]=++clj; die[dian]=ba; ss.push(dian); //int jiance=0; //if(tu[dian].size()>1)jiji[dian]++; for(int a=0;a<tu[dian].size();a++) { if(!dfn[tu[dian][a]]) { // jiance=1; tarjan(tu[dian][a],dian); low[dian]=min(low[dian],low[tu[dian][a]]); } else if(ba!=tu[dian][a]) { if(low[dian]>=low[tu[dian][a]]) { low[dian]=low[tu[dian][a]]; } } } if(low[dian]==dfn[dian]) { jc++; for(;;) { int ww=ss.top(); ss.pop(); sd[ww]=jc; if(ww==dian)break; } } //if(!jiance)yezi[dian]=1;}int main(){ int n,m; memset(dfn,0,sizeof(dfn)); memset(low,0,sizeof(low));// memset(yezi,0,sizeof(yezi)); memset(die,0,sizeof(die));// memset(jiji,0,sizeof(jiji)); memset(ppp,0,sizeof(ppp)); clj=0,jc=0; cin>>n>>m; int q,w; for(int a=1;a<=m;a++) { scanf("%d%d",&q,&w); if(mmm[q][w])continue; tu[q].push_back(w); tu[w].push_back(q); mmm[q][w]=mmm[w][q]=1; } tarjan(1,0);// for(int a=1;a<=n;a++)cout<<sd[a]<<" ";// cout<<endl; for(int a=1;a<=n;a++) { for(int b=0;b<tu[a].size();b++) { if(sd[a]==sd[tu[a][b]])continue; if(ppp[sd[a]][sd[tu[a][b]]])continue; ppp[sd[a]][sd[tu[a][b]]]=ppp[sd[tu[a][b]]][sd[a]]=1; xt[sd[a]].push_back(sd[tu[a][b]]); xt[sd[tu[a][b]]].push_back(sd[a]); } } int ye=0; for(int a=1;a<=jc;a++) { if(xt[a].size()==1)ye++; } cout<<(ye+1)/2<<endl; return 0;}
- poj3177 tarjan双联通缩点
- POJ3177 Redundant Paths (双联通缩点)
- poj3177—Redundant Paths(缩点+边双联通分量)
- POJ3177 Redundant Paths【边双联通分量】【Tarjan】
- POJ3177 Redundant Paths —— 边双联通分量 + 缩点
- poj3177 tarjan缩点+割边 模板 【pascal】
- 强联通分量 缩点 tarjan算法
- poj1236|poj3177 tarjan,强联通,有向/无向
- poj3177 - Redundant Paths-tarjan缩点+求度为1的点
- Tarjan点的双联通(寻找割点)
- poj3177 Redundant Paths(边双联通)
- hdu 3836 Equivalent Sets 强联通 tarjan缩点
- BZOJ 2438 杀人游戏 强联通分量tarjan缩点
- 强联通分量 缩点 tarjan 入门题小集
- BZOJ 1123: [POI2008]BLO 点双联通,Tarjan求割点
- poj3177 Redundant Paths 简单双联通求桥
- Tarjan边的双联通
- HDOJ 1827 - Summer Holiday 简单的tarjan求强联通分量+缩点
- 最长递增子序列(包含路径记录)
- Missing com.sun.jdmk:jmxtools:jar:1.2.1
- Android的RecyclerView基本应用
- VS运行时一闪而过的问题
- 2016.12.03
- poj3177 tarjan双联通缩点
- css学习之一使用自定义字体
- Python学习记录day6
- pputy远程登录linux自动掉线解决
- 内部链接十二条网页黄金规则
- How To Ask Question
- VC6.0在Realse版本下调试,需设置如下
- 数据库下载
- 25-文件与目录总结