hdu 1232畅通工程

用到并查集 所以记录下 好久没用这个了

#include<stdio.h>#include<string.h>int u[1005];int find_father(int x){while(u[x]!=-1){x=u[x];}return x;}int main(){int n,m,i,j,a,b,sum;while(scanf("%d",&n)!=EOF,n){scanf("%d",&m);memset(u,-1,sizeof(u));while(m--){scanf("%d%d",&a,&b);a=find_father(a);b=find_father(b);if(a!=b){u[a]=b;}}sum=0;for(i=1;i<=n;i++){if(u[i]==-1)sum++;}if(sum)printf("%d\n",sum-1);elseprintf("0\n");}return 0;}