hdu 1232 变成生成树至少还要加几条边 （并查集模板题）

 1 # include <iostream>
 2 # include <cstdio>
 3 # include <cstring>
 4 # include <algorithm>
 5 # include <cmath>
 6 # include <queue>
 7 # define LL long long
 8 using namespace std ;
 9 
10 const int MAXN=1010;
11 int F[MAXN];
12 int find(int x)
13 {
14     if(F[x]==-1) return x;
15     return F[x]=find(F[x]);
16 }
17 void bing(int u,int v)
18 {
19     int t1=find(u);
20     int t2=find(v);
21     if(t1!=t2) F[t1]=t2;
22 }
23 int main()
24 {
25     //freopen("in.txt","r",stdin) ;
26     int n,m;
27     while(scanf("%d",&n),n)
28     {
29         int i ;
30         scanf("%d",&m);
31         for(i=1;i<=n;i++)
32             F[i]=-1;
33         int u,v;
34         while(m--)
35         {
36             scanf("%d%d",&u,&v);
37             bing(u,v);
38         }
39         int res=0;
40         for(i=1;i<=n;i++)
41           if(F[i]==-1)
42              res++;
43         printf("%d\n",res-1);
44     }
45     return 0;
46 }