http://acm.split.hdu.edu.cn/showproblem.php?pid=1272
整個文件以兩個-1結尾。
#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
const int inf = 0x7fffffff;
#define ms(x) memset((x),0,sizeof(x))
const int Max = 100001;
int fa[Max];
int vfa[Max];
bool flag = false;
int fi(int x){
return fa[x]==x?x:fa[x]=fi( fa[x] );
}
void Lian(int x,int y){
int p1=fi(x),p2=fi(y);
if( p1 == p2 ) { flag = true; return;}
fa[p1]=p2;
}
void init(){
for(int i = 0;i < Max;i++) fa[i] = i;
ms(vfa); flag = false;
}
int main(){
// freopen("1.txt","r",stdin);
int a,b;
init();
while(scanf("%d%d",&a,&b)){
if( a==-1&&b==-1 ) break;
else if( a==0 && b==0 ){
if( flag ) puts("No");
else{
int cnt = 0;
for(int i = 1;i < Max;i++){
if( vfa[i] && fa[i] == i ) cnt++;
}
if( cnt > 1 ) puts("No");
else puts("Yes");
}
init();
}
else{
Lian(a,b);
vfa[a]=vfa[b]=1;
}
}
return 0;
}
void BingChaJI(){
int fi(int x){
return fa[x]==x?x:fa[x]=fi( fa[x] );
}
void Lian(int x,int y){
int p1=fi(x),p2=fi(y);
if( p1 == p2 ) return;
fa[p1]=p2;
}
int check(int x,int y){
int p1=fi(x),p2=fi(y);
if( p1 == p2 ) return 1;
return 0;
}
void init(){
for(int i = 0;i < maxn;i++) fa[i] = i;
}
}