hdu--1231--并查集<连分量的个数>

 1 #include <iostream>
 2 #include <cstring>
 3 using namespace std;
 4 
 5 const int size = 1010;
 6 int father[size];
 7 
 8 int find( int x )
 9 {
10     return father[x] == -1 ? x : father[x] = find( father[x] );
11 }
12 
13 void Union( int x , int y )
14 {
15     x = find(x);
16     y = find(y);
17     if( x!=y )
18     {
19         father[x] = y;
20     }
21 }
22 
23 int main()
24 {
25     int t , n , m , cnt , x , y;
26     cin >> t;
27     while( t-- )
28     {
29         cnt = 0;
30         cin >> n >> m;
31         memset( father , -1 , sizeof(father) );
32         while( m-- )
33         {
34             cin >> x >> y;
35             Union( x, y );
36         }
37         for( int i = 1 ; i<=n ; i++ )
38         {
39             if( father[i] == -1 )
40             {
41                 cnt ++;
42             }
43         }
44         cout << cnt << endl;
45     }
46     return 0;
47 }