uva 10397 Connect the Campus kruskal 算法变形

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <queue>
#include <stack>
#include <cstdlib>
#include <cmath>
#include <set>
#include <map>
#include <vector>
#include <cstring>

#define INF 100000000
using namespace std;
int n,m;
int x[1005];
int y[1005];
int fa[1005];

struct node{
	int x,y,w;

	bool operator < (const node& a)const{
		return w > a.w;
	}
};

int fun(int x){
	return fa[x] == x ? x : fa[x] = fun(fa[x]);
}
int main(){
	while(cin >> n){
		for(int i = 1;i <= n;i++){
			scanf("%d%d",&x[i],&y[i]);
		}
		priority_queue<node> que;

		for(int i = 1;i <= n;i++){
			for(int j = 1;j <= n;j++){
				if(i == j) continue;
				node a;
				a.x = i;
				a.y = j;
				a.w = (x[i]-x[j])*(x[i]-x[j]) + (y[i]-y[j])*(y[i]-y[j]);
				que.push(a);

			}
		}

		for(int i = 1;i <= n;i++){
			fa[i] = i;
		}
		int m;
		cin >> m;

		for(int i = 0;i < m;i++){
			int a,b;

			scanf("%d%d",&a,&b);
			fa[fun(a)] = fun(b);
		}
		double ret = 0;

		while(!que.empty()){
			node a = que.top();
			que.pop();
		 	if(fun(a.x) != fun(a.y)){
				ret += sqrt(a.w);
				fa[fun(a.x)] = fun(a.y);
		 	}
		}

		printf("%.2f\n",ret);

	}
	return 0;
}