记录编号	21881	评测结果	AAAAAAAA
题目名称	最小密度路径	最终得分	100
用户昵称	lc	是否通过	通过
代码语言	C++	运行时间	0.078 s
提交时间	2010-11-15 18:09:36	内存使用	1.15 MiB

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<algorithm>
using namespace std;
const int maxn = 60,INF = 1000000000;
int N,M,Q;
int Map[maxn][maxn];
bool Reach[maxn][maxn];
int F[maxn][maxn][maxn];


void prep()
{
	scanf("%d%d",&N,&M);
	for (int i=1; i<=N; i++)
		for (int j=1; j<=N; j++)
			for (int L=1; L<=N; L++)
				F[i][j][L] = INF;
	for (int x=1; x<=N; x++) F[x][x][0] = 0;
	for (int i=1; i<=M; i++)
	{
		int x,y,u;
		scanf("%d%d%d",&x,&y,&u);
		F[x][y][1] = u < F[x][y][1] ? u : F[x][y][1];
		Reach[x][y] = true;
	}
}

void work()
{
	for (int L=2; L<=N; L++)
		for (int x=1; x<=N; x++)
			for (int y=1; y<=N; y++)
				for (int P=1; P<=N; P++)
				{
					F[x][y][L] = min(F[x][y][L], F[x][P][L-1] + F[P][y][1] );
					Reach[x][y] = Reach[x][y] || (F[x][y][L]!=INF);
				}
}

void query()
{
	scanf("%d",&Q);
	for (int i=1; i<=Q; i++)
	{
		int x,y;
		scanf("%d%d",&x,&y);
		if (!Reach[x][y])
		{
			printf("OMG!\n"); continue;
		}

		double ave = INF;
		for (int L=1; L<=N; L++)
			if ((double)F[x][y][L]/L < ave)
				ave = (double)F[x][y][L] / L;
		printf("%.3f\n",ave);
	}
}

int main()
{
	freopen("path.in","r",stdin);
	freopen("path.out","w",stdout);
	prep();
	work();
	query();
	return 0;
}