HDU 1269 迷宫城堡 -- 强连通图判断

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题目地址：http://acm.hdu.edu.cn/showproblem.php?pid=1269

图的强连通分量
http://baike.baidu.com/link?url=NqsmNsGCotb9HUFgYdX1glgerL2cNjCe_OANCijjZLm8bjtmgrQ3DCPwNqMZz-S1GJ8lyAKPLDck8t5hsKXp2a
kosaraju算法
http://baike.baidu.com/link?url=JAN1OaKp_iwWknC2Q8NuQNT3hXnEm13kQaXKI724FjtjeGcrj90H4vAb-n7VMpOZ7zakYGhCwLg58Ad5AOnq5a

/*迷宫城堡http://acm.hdu.edu.cn/showproblem.php?pid=1269*/#include<stdio.h> #include<stdlib.h>#include<vector>#include<iostream>#include<stack>using namespace std;#define N 10005int n , m ;vector<int> v[N] ,r_v[N]; // 原图 和 逆向图int cnt ;bool visit[N];bool flag ;bool dfs(int rt,vector<int> *graph){    stack<int> sta;    sta.push(rt);    visit[rt] = true;    cnt = 0 ;    while(!sta.empty())    {        int now_u = sta.top();        cnt++;        sta.pop();        for(int i= 0 ; i < (int)graph[now_u].size() ; i++)        {            if( !visit[graph[now_u][i]])            {                sta.push(graph[now_u][i]);                visit[graph[now_u][i]] = true;            }        }    }    if(cnt == n )        return true;    return false;}bool kosaraju()  {      memset(visit, 0, sizeof(visit));      bool ret = dfs(1, v);      if (!ret)        return false;      memset(visit, 0, sizeof(visit));      ret = dfs(1, r_v);      if (ret)        return true;      return false;  }  int main()  {      //freopen("in.txt","r",stdin);    int i,j;      while(scanf("%d%d",&n,&m) != EOF)      {         if(n == 0 && m == 0 )            break;        int a , b;        for(i = 1; i <= n ; i++)        {            v[i].clear();            r_v[i].clear();        }        for(i = 0; i < m ; i++)        {            scanf("%d%d",&a,&b);            v[a].push_back(b);            r_v[b].push_back(a);        }        if(kosaraju())              printf("Yes\n");          else              printf("No\n");      }      return 0;  }

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