poj 1611 求0号结点所在集合的元素个数

求0号结点所在集合的元素个数

Sample Input

100 4
2 1 2
5 10 13 11 12 14
2 0 1
2 99 2
200 2
1 5
5 1 2 3 4 5
1 0
0 0
Sample Output

4
1
1

 1 # include <iostream>
 2 # include <cstdio>
 3 # include <cstring>
 4 # include <algorithm>
 5 # include <cmath>
 6 # include <queue>
 7 # define LL long long
 8 using namespace std ;
 9 
10 const int MAXN = 30010;
11 int F[MAXN];
12 int num[MAXN] ;
13 
14 int find(int x)//找x的祖先结点
15 {
16     if(F[x]==x) return x;
17     return F[x]=find(F[x]);
18 }
19 void bing(int u,int v) //按秩合并
20 {
21     int x = find(u);
22     int y = find(v);
23     if(x == y)
24         return ;
25     if(num[x] >= num[y])
26     {
27         F[y] = x;
28         num[x] += num[y];
29     }
30     else
31     {
32         F[x] = y;
33         num[y] += num[x];
34     }
35 }
36 int main()
37 {
38    // freopen("in.txt","r",stdin) ;
39     int n , m , k ;
40     while(scanf("%d %d", &n , &m) != EOF)
41     {
42          if (n == 0 && m == 0)
43              break ;
44 
45          int i ;
46          for(i = 0 ; i < n ; i++)
47          {
48              F[i] = i ;
49              num[i] = 1 ;
50          }
51         int u , v ;
52         while(m--)
53         {
54             scanf("%d %d" , &k , &u) ;
55             k-- ;
56             while(k--)
57             {
58                 scanf("%d" , &v) ;
59                 bing(u , v) ;
60             }
61         }
62         printf("%d
" , num[find(0)]) ; //集合元素的个数保存在祖先结点的num数组里
63 
64 
65     }
66     return 0;
67 }

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