hdu 1272 小希的迷宫(并查集 最小生成树)

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
#define maxn 100000
int fa[maxn+10];
int num[maxn+10];
int vis[maxn+10];
int ans,coun;
int find(int x)
{
return fa[x]=(x==fa[x]?x:find(fa[x]));
}
void fun(int x,int y)
{
int fx=find(x);
int fy=find(y);
if(fx==fy)
{
ans=0;
return ;
}
if(vis[x]==0) {vis[x]++;coun++;}
if(vis[y]==0) {vis[y]++;coun++;}
fa[fx]=fa[fy];
num[fy]+=num[fx];
if(num[fy]>ans) ans=num[fy];
}
int main()
{
int n;
int l,r;
int i,j,k;
while(scanf("%d%d",&l,&r)!=EOF)
{
if(l==0&&r==0) {printf("Yes\n"); continue;}
if(l==-1&&r==-1) break;
ans=1;
coun=0;
for(i=0;i<=maxn;i++) {fa[i]=i;num[i]=1;}
memset(vis,0,sizeof(vis));
while(l!=0||r!=0)
{
if(ans)
fun(l,r);
scanf("%d%d",&l,&r);
}
if(ans==coun) printf("Yes\n");
else printf("No\n");
}
return 0;
}