hdu1856 More is better

#include <stdio.h>
//求并查集,元素最多的集合
struct node
{
	int a,b;
}arr[100002];

int father[10000002],rank[10000002];

int find(int x)
{
	if(father[x]!=x)  
		father[x]=find(father[x]);  
	return father[x];
}
int main()
{
	int n,i,ans;
	while(scanf("%d",&n)!=EOF)
	{
		int MAXNUM=1;
		ans=0;
		for (i=1;i<=n;i++)
		{
			scanf("%d %d",&arr[i].a,&arr[i].b);
			if(arr[i].a>MAXNUM)
				MAXNUM=arr[i].a;
			else if(arr[i].b>MAXNUM)
				MAXNUM=arr[i].b;
		}
		for (i=1;i<=MAXNUM;i++)
		{
			father[i]=i;
			rank[i]=1;//每个集合元素个数,或深度
		}
		for (i=1;i<=n;i++)
		{
			int x=find(arr[i].a);
			int y=find(arr[i].b);
			if(x!=y)
			{
				father[x]=y;
				rank[y]+=rank[x];
			}
		}
		for(i=1;i<=MAXNUM;i++)
		{
			if(father[i]==i)
				if(rank[i]>ans)
					ans=rank[i];
		}
		printf("%d\n",ans);
	}
	return 0;
}