poj1611 The Suspects（并查集）

 1 #include <iostream>
 2 #include <cstring>
 3 #include <cstdio>
 4 using namespace std;
 5 
 6 const int N = 30000 + 10;
 7 int p[N];
 8 
 9 void make_set(int n)
10 {
11     for (int i = 0; i < n; i++)
12         p[i] = i;
13 }
14 
15 int find_root(int x)
16 {
17     if (x == p[x])
18         return x;
19     else
20     {
21         int temp = find_root(p[x]);        //路径压缩
22         p[x] = temp;
23         return temp;
24     }
25 }
26 
27 void union_set(int x, int y)
28 {
29     int px = find_root(x);
30     int py = find_root(y);
31     if (px != py)
32         p[px] = py;
33 }
34 
35 int main()
36 {
37     freopen("poj1611.txt", "r", stdin);
38     int n, m;
39     while (scanf("%d%d", &n,&m)==2 && n)
40     {
41         make_set(n);
42         for (int i = 0; i < m; i++)
43         {
44             int k;
45             int x, y;
46             scanf("%d%d", &k, &x);
47             for (int j = 1;j < k;j++)
48             {
49                 scanf("%d", &y);
50                 union_set(x, y);
51                 x = y;
52             }
53         }
54         int root = find_root(0);
55         int ans = 0;
56         for (int i = 0; i < n; i++)
57             if (find_root(i) == root)
58                 ans++;
59         cout << ans << endl;
60     }
61     return 0;
62 }