并查集 HDU 1856

#include<iostream>
#include<stdio.h>
using namespace std;

int father[10000001],num[10000001];


/**//*初始化数组*/
void makeset(int x)
{
 for(int i=0;i<=x;i++)
 {
 father[i]=i;
 num[i]=1;
 }
}


int findset(int x)//查
{
 if(x!=father[x])
 {
 father[x]=findset(father[x]);
 }//回溯
 return father[x];
}


void Union(int a,int b)//并
{
 int x=findset(a);
 int y=findset(b);
 if(x==y)
 {
 return;
 }
 if(num[x]>=num[y])
 {
 father[y]=x;
 num[x]+=num[y];
 }
 else
 {
 father[x]=y;
 num[y]+=num[x];
 }
 }


int main()
{ int n;

 while(scanf("%d",&n)!=EOF)
 {
 makeset(10000000);
 for(int i=1;i<=n;i++)
 {
 int first,second;
 scanf("%d%d",&first,&second);
 Union(first,second);
 }
 int max=-99999;
 for(int i=1;i<=10000000;i++)
 {
 if(num[i]>max)
 max=num[i];
 }
 printf("%d\n",max);
 }
 return 0;
}