bzoj 1050 并查集

#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
struct edgee
{
	int from, to ;
	double value;
}edge[5001];
bool com(edgee a, edgee b)
{
	return a.value < b.value;
}
int fa[501];
int n, m,s,t;
int realmax, realmin;
void init()
{
	for (int i = 1; i <= n; i++)
	{
		fa[i] = i;
	}
}
int find(int x)
{
	if (fa[x] == x)
		return x;
	else
	{
		return fa[x] = find(fa[x]);
	}
}
void unionn(int x, int y)
{
	x = find(x);
	y = find(y);
	if (x == y)
		return;
	fa[y] = x;
}
bool issame(int x, int y)
{
	return find(x) == find(y);
}
int  extgcd(int x, int y)
{
	if (x < y)
		swap(x, y);
	if (y == 0)
		return x;
	else
		return extgcd(y, x%y);
}
int main()
{
	scanf("%d%d", &n, &m);
	for (int i = 0; i < m; i++)
	{
		int a, b;
		double c;
		scanf("%d%d%lf", &a, &b, &c);
		edge[i].from = a;
		edge[i].to = b;
		edge[i].value = c;
	}

	scanf("%d%d", &s, &t);
	sort(edge, edge + m, com);
	double ans = 1000000000;
	
	for (int i = 0; i < m; i++)
	{
		init();//并查集遗忘初始化
		double maxx;
		double minn = edge[i].value;
		for (int j = i; j < m; j++)
		{
			maxx = edge[j].value;//这写成了edge[i].value
			unionn(edge[j].from, edge[j].to);//这写成了edge[i].to,edge[i].from
			if (issame(s, t))
			{
				if (ans>(maxx / minn))
				{
					ans = maxx / minn;
					realmax = maxx;
					realmin = minn;
				}
			}
		}
	}
	int temp = extgcd((int)realmax, (int)realmin);
	if (ans == 1000000000)
		printf("IMPOSSIBLE\n");
	else
	{
		if (((int)realmax) % ((int)realmin) == 0)
			printf("%d\n", (int)(realmax / realmin));
		else
		{
			int tempmax = (int)(realmax / temp);
			int tempmin = (int)(realmin / temp);
			printf("%d/%d\n", tempmax, tempmin);
		}
	}
}

这题就是暴力先开始还以为是最短路 我还是太too young 了。。。 话说跑得真是巨慢呢。。。。。。