1072 Gas Station [dj]

题目大意：找出加油站要尽可能远离居民区 输出这个加油站到居民区最短距离和平均距离

#include<iostream>
#include<vector>
#include<queue>
#include<stack>
#include<string>
#include<math.h>
#include<algorithm>
#include<map>
#include<cstring>
#include<set>
using namespace std;
const int maxn = 1011;
const int inf = 1000000001;
int n, m, k, ds;
int d[maxn];
int G[maxn][maxn];
bool vis[maxn];

void dj(int s)
{
	memset(vis, false, sizeof(vis));
	fill(d, d + maxn, inf);
	d[s] = 0;
	for (int i = 1; i <= n+m; i++)
	{
		int u = -1, min = inf;
		for (int j = 1; j <= n + m; j++)
		{
			if (vis[j] == false && d[j] < min)
			{
				u = j;
				min = d[j];
			}
		}
		if (u == -1) return;
		vis[u] = true;
		for (int v = 1; v <= n + m; v++)
		{
			if (vis[v] == false)
			{
				if (d[u] + G[u][v] < d[v])
				{
					d[v] = d[u] + G[u][v];
				}
			}
		}
	}
}
int strtoInt(string s)
{
	int i = 0, len = s.size(), id = 0;
	while (i < len)
	{
		if (s[i] != 'G')
		{
			id = id * 10 + (s[i] - '0');
		}
		i++;
	}
	if (s[0] == 'G') return n + id;
	else return id;
}
int main()
{
	cin >> n >> m >> k >> ds;
	string s1, s2;
	int u, v, q;
	fill(G[0], G[0] + maxn * maxn, inf);
	for (int i = 1; i <= k; i++)
	{
		cin >> s1 >> s2 >> q;
		u = strtoInt(s1);
		v = strtoInt(s2);
		G[u][v] = G[v][u] = q;
	}

	double Mindis = -1, id = -1, Avq = inf;
	for (int i = n + 1; i <= n + m; i++)
	{
		double mindis = inf, avq = 0;
		dj(i);
		for (int j = 1; j <= n; j++)
		{
			if (d[j] > ds)
			{
				mindis = -1;
				break;
			}
			if (d[j] < mindis)
			{
				mindis = d[j];
			}
			avq += 1.0 * d[j] / n;
		}
		if (mindis == -1) continue;
		if (mindis > Mindis)
		{
			id = i;
			Mindis = mindis;
			Avq = avq;
		}
		else if (mindis == Mindis && avq < Avq)
		{
			id = i;
			Avq = avq;
		}
	}
	if (id == -1) cout << "No Solution" << endl;
	else
	{
		cout << "G"<< id - n << endl;
		printf("%.1f %.1f
", Mindis, Avq);
	}
	return 0;
}