杭电1213题解：一道最基础的并查集问题

 1 #include <iostream>
 2 #include <cstring>
 3 
 4 using namespace std;
 5 int id[1005];
 6 int tree(int x)
 7 {
 8     while(id[x]!=x)
 9     {
10         x = id[x];
11     }
12     return id[x];
13 }
14 
15 int main()
16 {
17     int T;
18     int i = 0, j = 0;
19     int n, m;
20 
21     int mi, mj;
22     int counts;
23     cin >> T;
24     for(i=0; i<T; i++)
25     {
26         counts = 0;
27         memset(id, 0, sizeof(id));
28         cin >> n >> m;
29         for(j=0; j<=n; j++){
30             id[j] = j;
31         }
32         for(j=1; j<=m; j++)
33         {
34             cin >> mi >> mj;
35             id[tree(mi)] = id[tree(mj)];
36         }
37         for(j=1; j<=n; j++)
38         {
39             if(id[j]==j)
40                counts++;
41         }
42 
43         cout << counts << endl;
44     }
45     return 0;
46 }