hdu 1856 求集合里元素的个数 输出最大的个数是多少

求集合里元素的个数 输出最大的个数是多少

Sample Input
4
1 2
3 4
5 6
1 6
4
1 2
3 4
5 6
7 8

Sample Output
4
2

 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 = 10000010;
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 ;
40     while(scanf("%d",&n) != EOF)
41     {
42          if (n == 0)
43          {
44              printf("1\n") ;
45              continue ;
46          }
47          int i ;
48          for(i = 1 ; i <= MAXN ; i++)
49          {
50              F[i] = i ;
51              num[i] = 1 ;
52          }
53         int u , v , t = 0 ;
54         for(i = 1 ; i <= n ; i++)
55         {
56             scanf("%d %d" , &u , &v) ;
57             bing(u,v) ;
58             t = max(t , max(u , v)) ;
59         }
60         int Max = 0 ;
61         for(i = 1 ; i <= t ; i++)
62             if (num[i] > Max)
63                Max = num[i] ;
64         printf("%d\n" , Max) ;
65
66     }
67     return 0;
68 }