2066 三角恋

#include<cstdio>
#include<iostream>
#include<stack>
#include<vector>
#include<cstring>
#define M 2016
using namespace std;
vector<int> grap[M];
stack<int> s;
char ch[M];
int low[M],num[M],vis[M],instack[M],map[M][M],f[M],n,cnt,tot;
void tarjan(int v)
{
    low[v]=num[v]=++tot;
    s.push(v);
    instack[v]=1;
    vis[v]=1;
    for(int i=0;i<grap[v].size();i++){
        int w=grap[v][i];
        if(!vis[w]){
            tarjan(w);
            low[v]=min(low[v],low[w]);
        }
        else if(instack[w])
          low[v]=min(low[v],num[w]);
    }
    int u;
    if(low[v]==num[v]){
        ++cnt;
        do
        {
            u=s.top();
            f[cnt]++;
            s.pop();
            instack[u]=0;
        }while(u!=v);
    }
}
void init(){
    int x;
    scanf("%d",&n);
    for(int i=1;i<=n;i++){
        scanf("%s",ch);
        for(int j=1;j<=n;j++)
          map[i][j]=(int)ch[j-1]-‘0‘;
    }
    for(int i=1;i<=n;i++)
       for(int j=1;j<=n;j++)
          if(map[i][j]==1)grap[j].push_back(i);
    for(int i=1;i<=n;i++)
       if(!vis[i])tarjan(i);
    if(cnt<n)printf("Yes\n");
    else printf("No\n");
    for(int i=1;i<=n;i++)grap[i].clear();
}
int main(){
    int t;
    scanf("%d",&t);
    for(int i=1;i<=t;i++){
        cnt=0;
        memset(vis,0,sizeof(vis));
        memset(low,0,sizeof(low));
        memset(num,0,sizeof(num));
        memset(instack,0,sizeof(instack));
        memset(f,0,sizeof(f));
        init();
    }
    return 0;
}