More is better

4
1 2
3 4
5 6
1 6
4
1 2
3 4
5 6
7 8

4
2

Hint
A and B are friends(direct or indirect), B and C are friends(direct or indirect), 
then A and C are also friends(indirect).

 In the first sample {1,2,5,6} is the result.
In the second sample {1,2},{3,4},{5,6},{7,8} are four kinds of answers.
 
 

一个并查集 计算每一个集合的元素 找出元素最多的那个集合，输出元素的个数

输入n=0时也应该输出1

难点就在于，怎么计算集合的元素个数。

。事实上仅仅要在初始的时候每一个元素都初始为1。

然后合并集合的时候+1就好了

#include <stdio.h>
#include <string.h>
#define N 10000000+5
int fa[N],stamp[N];
int find(int x)
{
	if(fa[x]!=x) fa[x]=find(fa[x]);
	return fa[x];
}
void init()
{
	for(int i=1;i<=N;i++)
	fa[i]=i,stamp[i]=1;
}
int main()
{
	int n,min,max;
	while(~scanf("%d",&n))
	{
		init();
		min=10000000+5,max=-1;
		for(int i=0;i<n;i++)
		{
			int a,b;
			scanf("%d %d",&a,&b);
			a=find(a),b=find(b);
			if(a!=b)
			fa[a]=b,stamp[b]+=stamp[a];
			if(a>max) max=a;
			if(b>max) max=b;
			if(a<min) min=a;
			if(b<min) min=b;
		}
		int count=1;
		for(int i=min;i<=max;i++)
		{
			if(stamp[i]>count)
			count=stamp[i];
		}
		printf("%d\n",count);
	}
	return 0;
}