HDU 1213 How Many Tables

 1 #include<stdio.h>
 2 #define LEN 10000
 3 
 4 int p[LEN];
 5 
 6 int _find(int x) {
 7     return p[x] == x ? x : (p[x] = _find(p[x]));
 8 }
 9 
10 int main() {
11     int num, ans, i, j;
12     scanf("%d", &num);
13     while(num--){
14         int n, m;
15         scanf("%d%d", &n, &m);
16         for(i = 1; i <= n; i++)
17             p[i] = i;
18         for(i = 0; i < m; i++){
19             int a, b, t1, t2;
20             scanf("%d%d", &a, &b);
21             t1 = _find(a);
22             t2 = _find(b);
23             if(t1 != t2)
24                 p[t1] = t2;
25         }
26         ans = 0;
27         for(i = 1; i <= n; i++)
28             if(i == p[i])
29                 ans++;
30         printf("%d\n", ans);
31     }
32     return 0;
33 }