Uva 796 Critical Links 找桥

这个题很简单，但是输入有毒，用字符串的我一直RE

然后换成这样瞬间AC

#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <math.h>
#include <vector>
#include <stack>
using namespace std;
typedef long long LL;
const int N = 1e4+5;
int head[N],tot,n,cnt;
struct Edge{
   int u,v,next;
   bool operator<(const Edge& rhs)const{
     if(u!=rhs.u)return u<rhs.u;
     return v<rhs.v;
   }
}edge[N*10],o[N*10];
void add(int u,int v){
   edge[tot].v=v;
   edge[tot].next=head[u];
   head[u]=tot++;
}
int dfn[N],low[N],clk;
void targin(int u,int f){
   dfn[u]=low[u]=++clk;
   for(int i=head[u];~i;i=edge[i].next){
       int v=edge[i].v;
       if(v==f)continue;
       if(!dfn[v]){
         targin(v,u);
         low[u]=min(low[u],low[v]);
         if(dfn[u]<low[v]){
            ++cnt;
            o[cnt].u=min(u,v);
            o[cnt].v=max(u,v); 
         }
       }
       else if(dfn[v]<low[u])low[u]=dfn[v];
   }
}
int main(){
    while(~scanf("%d",&n)){
      memset(head,-1,sizeof(head));
      cnt=clk=tot=0;
      for(int i=1;i<=n;++i){
         int u,k;
         scanf("%d (%d)",&u,&k);
         while(k--){int v;scanf("%d",&v);add(u,v);}
      }
      memset(dfn,0,sizeof(dfn));
      memset(low,0,sizeof(low));
      for(int i=0;i<n;++i)
       if(!dfn[i])targin(i,-1);
      printf("%d critical links
",cnt);
      if(cnt)sort(o+1,o+1+cnt);
      for(int i=1;i<=cnt;++i){
        printf("%d - %d
",o[i].u,o[i].v);
      }
      printf("
");
    }
    return 0;
}