hdu4324 Triangle LOVE【tarjan强连通分量基础题】

/**********
hud4324
**********/
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int M=4e6+10,N=2e3+10;
int head
,ed;
char str[2006][2006];
struct node{
int to,next;
}edge[M];
int sta
,vis
,low
,dfn
,top; //,out

void init(){
ed=0;
memset(head,-1,sizeof(head));
memset(edge,0,sizeof(edge));
memset(sta,0,sizeof(sta));
}
void addedge(int a,int b){
edge[ed].to=b;
edge[ed].next=head[a];
head[a]=ed++;
}
void tarbfs(int k,int cnt,int &num){
vis[k]=1;
low[k]=cnt;
dfn[k]=cnt;
sta[top++]=k;
for(int i=head[k];i>-1;i=edge[i].next){
if(vis[edge[i].to]==0) tarbfs(edge[i].to,++cnt,num);
if(vis[edge[i].to]==1) low[k]=min(low[k],low[edge[i].to]);
}
if(dfn[k]==low[k]){
++num;
while(top>0&&sta[top]!=k){
//printf("%d  ",sta[top]);
top--;
low[sta[top]]=num;
vis[sta[top]]=2;
}//
}
}
int tarjan(int n){
int num=0,cnt=1;
top=0;
memset(vis,0,sizeof(vis));
memset(low,0,sizeof(low));
for(int i=1;i<=n;i++){
if(vis[i]==0) tarbfs(i,cnt,num);
}
return num;
}

int main()
{
//  freopen("cin.txt","r",stdin);
int n,m,t,b;

scanf("%d",&t);
b=1;
while(t--){
int a;
init();
scanf("%d",&n);
for(int i=1;i<=n;i++)
scanf("%s",str[i]+1);
for(int i=1;i<=n;i++)
for(int j=1;j<=n;j++)
if(str[i][j]=='1')
addedge(i,j);
/*for(int i=1;i<=ed;i++)
{
for(int k=head[i];k!=-1;k=edge[k].next)
printf("u=%d v=%d    ",i,edge[k].to);
printf("\n");
}*/
int num=tarjan(n);
//printf("%d   ",num);

printf("Case #%d: ",b++);
if(num>=1&&num!=n) puts("Yes");
else puts("No");
}
return 0;
}