poj 2492 A Bug's Life（带权并查集）

#include<iostream>
#include<cstdio>
#include<cstring>
#include<math.h>
#include<algorithm>
using namespace std;

const int INF=0x3f3f3f3f;
const int maxn=2005;
int T,n,m;
int f[maxn],sum[maxn];

void Make_Set(){
for(int i=1;i<=n;i++)
f[i]=i,sum[i]=0;
}

int find(int x){
if(f[x]!=x){
int tmp=f[x];
f[x]=find(f[x]);
sum[x]=(sum[tmp]+sum[x])%2;
}
return f[x];
}

bool Union(int a,int b){
int ra=find(a);
int rb=find(b);
if(ra==rb&&sum[a]==sum[b])
return false;
f[ra]=rb;
sum[ra]=(sum[b]-sum[a]+1)%2;
return true;
}

int main() {
#ifndef ONLINE_JUDGE
freopen("test.in","r",stdin);
freopen("test.out","w",stdout);
#endif
int cas=1;
scanf("%d",&T);
while(T--){
scanf("%d%d",&n,&m);
Make_Set();
bool flag=true;
int a,b;
while(m--){
scanf("%d%d",&a,&b);
if(!flag) continue;
if(!Union(a,b)) flag=false;
}
printf("Scenario #%d:\n",cas++);
if(!flag) printf("Suspicious bugs found!\n");
else printf("No suspicious bugs found!\n");
putchar(10);
}
return 0;
}