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

# include <iostream>
# include <cstdio>
# include <cstring>
# include <algorithm>
# include <cmath>
# include <queue>
# define LL long long
using namespace std ;

const int MAXN = 10000010;
int F[MAXN];
int num[MAXN] ;

int find(int x)//找x的祖先结点
{
    if(F[x]==x) return x;
    return F[x]=find(F[x]);
}
void bing(int u,int v) //按秩合并
{
    int x = find(u);
    int y = find(v);
    if(x == y)
        return ;
    if(num[x] >= num[y])
    {
        F[y] = x;
        num[x] += num[y];
    }
    else
    {
        F[x] = y;
        num[y] += num[x];
    }
}
int main()
{
    //freopen("in.txt","r",stdin) ;
    int n ;
    while(scanf("%d",&n) != EOF)
    {
         if (n == 0)
         {
             printf("1
") ;
             continue ;
         }
         int i ;
         for(i = 1 ; i <= MAXN ; i++)
         {
             F[i] = i ;
             num[i] = 1 ;
         }
        int u , v , t = 0 ;
        for(i = 1 ; i <= n ; i++)
        {
            scanf("%d %d" , &u , &v) ;
            bing(u,v) ;
            t = max(t , max(u , v)) ;
        }
        int Max = 0 ;
        for(i = 1 ; i <= t ; i++)
            if (num[i] > Max)
               Max = num[i] ;
        printf("%d
" , Max) ;

    }
    return 0;
}