#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
using namespace std;
const int maxn = 1000;
int f[maxn+10];
int getFather(int x) {
if(x == f[x]) return x;
else return f[x] = getFather(f[x]);
}
int gn, gm;
int main(void)
{
int x, y;
while(scanf("%d", &gn) == 1 && gn) {
scanf("%d", &gm);
for(int i = 1; i <= gn; i++) f[i] = i;
for(int i = 0; i < gm; i++) {
scanf("%d%d", &x, &y);
int t1 = getFather(x);
int t2 = getFather(y);
if(t1 != t2) {
f[t1] = t2;
}
}
int cnt = 0;
for(int i = 1; i <= gn; i++) {
if(f[i] == i) cnt++;
}
printf("%d\n", cnt-1);
}
return 0;
}
原文:http://blog.csdn.net/achiberx/article/details/21509683