POJ 1463 ||HDU 1054 Strategic game（二分图最小顶点覆盖）

#include<map>
#include<queue>
#include<cmath>
#include<iostream>
#include<cstdio>
#include<stack>
#include<cstring>
#include<algorithm>
#define LL __int64
#define inf 0x3f3f3f3f
const double PI=acos(-1.0);
using namespace std;

int cro[20000],head[20000],cnt;
bool vis[20000];

struct node{
int to,next;
}q[200000];
void bu(int k,int t){
q[cnt].to=t;
q[cnt].next=head[k];
head[k]=cnt++;

q[cnt].to=k;
q[cnt].next=head[t];
head[t]=cnt++;
}
bool dfs(int u){
for(int i=head[u];~i;i=q[i].next){
int v=q[i].to;
if(vis[v]) continue;
vis[v]=true;
if(cro[v]==-1||dfs(cro[v])){
cro[v]=u;
return true;
}
}
return false;
}
int main(){
int i,j,n,m,k,t;
while(~scanf("%d",&n)){
memset(head,-1,sizeof(head));
cnt=0;
for(i=0;i<n;++i){
scanf("%d:(%d)",&k,&m);
while(m--){
scanf("%d",&t);
bu(k,t);
}
}
int ans=0;
memset(cro,-1,sizeof(cro));
for(i=0;i<n;++i){
memset(vis,false,sizeof(vis));
if(dfs(i)) ans++;
}
printf("%d\n",ans/2);
}
return 0;
}
//2
//1:(1) 0
//0:(1) 1