HDU 1232 & 1213并查集应用 练习

并查集还是挺简单的，路径压缩，按秩合并（这个很麻烦，建议了解就好，主要是路径压缩，我写的代码也只是普通的合并）；

前天学的，要练练手，以防生疏；

http://acm.hdu.edu.cn/showproblem.php?pid=1232

#include <iostream>
#include <cstdio>
#define maxn 10010
#define INF 999999999
using namespace std;

int map[maxn][maxn],set[maxn];
int find(int x)
{
	if(set[x] == x)return x;
	return set[x] = find(set[x]);
}
int main()
{
	int n,m;
	while(scanf("%d",&n),n)
	{
		scanf("%d",&m);
		int a,b;
		for(int i =1; i <= n; i++)
			set[i] = i;
		for(int i = 1; i <= m; i++)
		{
			scanf("%d%d",&a,&b);
			int fa = find(a),fb = find(b);
			if(fa != fb)
				set[fa] = fb;
		}
		int count = 0;
		for(int i = 1; i <= n; i++)
		{
			if(set[i] == i)count++;
		}
		printf("%d\n",count-1);
	}
	return 0;
}

http://acm.hdu.edu.cn/showproblem.php?pid=1213

#include <iostream>
#include <cstdio>
#define maxn 1003
#define INF 999999999
using namespace std;

int map[maxn][maxn],set[maxn];
int find(int x)
{
	if(set[x] == x)return x;
	return set[x] = find(set[x]);
}
int main()
{
	int T,n,m;
	scanf("%d",&T);
	while(T--)
	{
		scanf("%d%d",&n,&m);
		for(int i =1; i <= n; i++)
			set[i] = i;
		int a,b;
		for(int i = 1; i <= m; i++)
		{
			scanf("%d%d",&a,&b);
			int fa = find(a),fb = find(b);
			if(fa != fb)
				set[fa] = fb;
		}
		int count = 0;
		for(int i = 1; i <= n; i++)
		{
			if(set[i] == i)count++;
		}
		printf("%d\n",count);
	}
	return 0;
}