hdu 1856 More is better

#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
using namespace std;
struct node
{
    int num,root;
}tree[10000005];

int find(int x)
{
    return x==tree[x].root?x:tree[x].root=find(tree[x].root);
}

void init()
{
    for (int i=0;i<=10000001;i++)
    {
        tree[i].num=0;
        tree[i].root=i;
    }
}

int main()
{
    int n,x,y,maxn;
    while (scanf("%d",&n)!=EOF)
    {
        init();
        maxn=0;
        for (int i=0;i<n;i++)
        {
            scanf("%d%d",&x,&y);
            maxn=max(maxn,x);
            maxn=max(maxn,y);
            x=find(x);
            y=find(y);
            if (x!=y) tree[x].root=y;
        }
        int ans=0;
        for (int i=0;i<=maxn;i++)
        {
            tree[find(i)].num++;
            if (ans<tree[find(i)].num) ans=tree[find(i)].num;
        }
        printf("%d\n",ans);
    }
    return 0;
}