HDU ACM 1856 More is better（并查集）

【题目链接】http://acm.hdu.edu.cn/showproblem.php?pid=1856

【解题思路】给的数据有点大，干脆少开点数组，直接上set存储有朋友的孩子的编号，同时根据编号初始化对应的在father数组中的下标，同时也更新集合，后面开一个数组存储同属于于一个集合的数有多少个（在以根为数组的下标中存储），然后遍历一次找到最大的数

#include <cstdio>
#include <cstring>
#include <set>
#include <algorithm>
#define SIZE 10000001
#define MAXN  100002
using namespace std;
int father[SIZE];
int num[SIZE];

set<int>exist;


int find(int f)
{
    return father[f] = f == father[f] ? f : find(father[f]);
}


int main()
{
    #ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    #endif
    int n;
    while(scanf("%d", &n) != EOF)
    {
        if(!n)
        {
            printf("1
");
            continue;
        }
        exist.clear();
        memset(num, 0, sizeof(num));
        for(int i=0; i<n; ++i)
        {
            int u, v;
            scanf("%d%d", &u, &v);
            if(exist.find(u) == exist.end())
            {
                father[u] = u;
                 exist.insert(u);
                 num[u] = 0;
            }
            if(exist.find(v) == exist.end())
            {
                 exist.insert(v);
                father[v] = v;
                num[v] = 0;
            }
            u = find(u);
            v = find(v);
            father[u] = v;
        }
        for(set<int>::const_iterator iter = exist.begin(); iter != exist.end(); ++iter)
        {
            num[find(*iter)]++;
        }
        int curmax = 0;
        for(set<int>::const_iterator iter = exist.begin(); iter != exist.end(); ++iter)
        {
            if(curmax < num[*iter]) curmax = num[*iter];
        }
        printf("%d
", curmax);
    }
    return 0;
}