POJ 2186 Popular Cows 强连通
来源:互联网 发布:linux大学时候开发 编辑:程序博客网 时间:2024/06/06 07:29
Popular Cows
Time Limit: 2000MS Memory Limit: 65536KTotal Submissions: 25060 Accepted: 10268
Description
Every 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 tell you that cow A thinks that cow B is popular. Since popularity is transitive, if A thinks B is popular and B thinks C is popular, then A will also think that C is
popular, even if this is not explicitly specified by an ordered pair in the input. Your task is to compute the number of cows that are considered popular by every other cow.
popular, even if this is not explicitly specified by an ordered pair in the input. Your task is to compute the number of cows that are considered popular by every other cow.
Input
* Line 1: Two space-separated integers, N and M
* Lines 2..1+M: Two space-separated numbers A and B, meaning that A thinks B is popular.
* Lines 2..1+M: Two space-separated numbers A and B, meaning that A thinks B is popular.
Output
* Line 1: A single integer that is the number of cows who are considered popular by every other cow.
Sample Input
3 31 22 12 3
Sample Output
1
Hint
Cow 3 is the only cow of high popularity.
Source
USACO 2003 Fall
周日时准备讲的
题意:求有向图中能被所有点到达的点数
缩点后,出度为0且唯一的连通块包含的点数为解-w-
/** Author: ☆·aosaki(*’(OO)’*) niconiconi★ **///#pragma comment(linker, "/STACK:1024000000,1024000000")//#include<bits/stdc++.h>#include <iostream>#include <sstream>#include <cstdio>#include <cstring>#include <algorithm>#include <functional>#include <cmath>#include <vector>#include <queue>#include <map>#include <set>#include <list>//#include <tuple>#define ALL(v) (v).begin(),(v).end()#define foreach(i,v) for (__typeof((v).begin())i=(v).begin();i!=(v).end();i++)#define SIZE(v) ((int)(v).size())#define mem(a) memset(a,0,sizeof(a))#define mem1(a) memset(a,-1,sizeof(a))#define lp(k,a) for(int k=1;k<=a;k++)#define lp0(k,a) for(int k=0;k<a;k++)#define lpn(k,n,a) for(int k=n;k<=a;k++)#define lpd(k,n,a) for(int k=n;k>=a;k--)#define sc(a) scanf("%d",&a)#define sc2(a,b) scanf("%d %d",&a,&b)#define lowbit(x) (x&(-x))#define ll long long#define pi pair<int,int>#define vi vector<int>#define PI acos(-1.0)#define pb(a) push_back(a)#define mp(a,b) make_pair(a,b)#define TT cout<<"*****"<<endl;#define TTT cout<<"********"<<endl;inline int gcd(int a,int b){ return a==0?b:gcd(b%a,a);}#define INF 1e9#define eps 1e-8#define mod 10007#define maxn 10010#define maxm 50010using namespace std;int v[maxn],col[maxn],ans[maxn];int rea[maxn],low[maxn],stack[maxn];int out[maxn];int n,m,tot=0,color,tm=0,index=0,top=0;int pre[maxn];struct Side{ int to,next;}e[maxm];void add(int u,int v){ e[tot].to=v; e[tot].next=pre[u]; pre[u]=tot++;}void tarjan(int i){ v[i]=1; top++; stack[top]=i; ++tm; rea[i]=tm; low[i]=tm; for(int j=pre[i];j!=-1;j=e[j].next) { int x=e[j].to; if(v[x]==0) tarjan(x); if(v[x]<2) low[i]=min(low[i],low[x]); } if(rea[i]==low[i]) { color++; int tt=0; while(stack[top+1]!=i) { tt++; col[stack[top]]=color; v[stack[top]]=2; top--; } ans[color]=tt; }}void init(){ mem(col); mem(v); mem1(pre); mem(rea); mem(low); tot=0; top=0; tm=0; index=0; color=0; mem(out);}int main(){ //freopen("in.txt","r",stdin); int uu,vv; while(~sc2(n,m)) { init(); lp(i,m) { sc2(uu,vv); add(uu,vv); } lp(i,n) if(!rea[i]) tarjan(i); if(color==1) { printf("%d\n",n); continue; } lp(i,n) { for(int j=pre[i];j!=-1;j=e[j].next) { int x=e[j].to; if(col[i]!=col[x]) out[col[i]]++; } } int re=0; lp(i,color) { if(!out[i]) { if(!re) re=ans[i]; else { re=0; break; } } } printf("%d\n",re); } return 0;}
0 0
- POJ 2186-Popular Cows ---强连通分量
- poj 2186 Popular Cows 强连通
- poj 2186 Popular Cows 强连通
- POJ 2186 Popular Cows / 强连通分量
- POJ 2186 Popular Cows 强连通分量
- POJ 2186 Popular Cows (强连通分量)
- POJ 2186 Popular Cows 强连通
- POJ 2186 Popular Cows (强连通分量)
- POJ 2186 Popular Cows(强连通)
- poj 2186 Popular Cows 【强连通】
- POJ 2186 Popular Cows(强连通)
- POJ 2186 Popular Cows (强连通分量)
- POJ -- 2186 Popular Cows(强连通)
- POJ 2186 Popular Cows 强连通
- POJ 2186 Popular Cows 强连通分量
- POJ 2186 Popular Cows 强连通分量
- poj 2186 Popular Cows 强连通分量
- POJ 2186 Popular Cows(强连通分量)
- Windows GDI:CGdiObject使用总结
- 框架开发2
- 常用算法之Trie【字典树,前缀树】
- CentOS安装图形界面
- Leetcode Isomorphic Strings
- POJ 2186 Popular Cows 强连通
- 初识GestureDetector
- “进程球”通过数据库来通信------好美的一幅图!
- BroadcastReceiver的生命周期:保存在Receiver中的static变量为什么老为空
- 黑马程序员(九) 异常及常见异常总结
- Windows GDI:CDC使用总结
- C++浅析——继承类中构造和析构顺序
- Java利用Callable、Future进行并行计算求和
- Windows GDI:CDC绘制文本