有关图的密度的规律

题目是这样的：
Description：

Input
The first line contains two space-separated integers n (1 ≤ n ≤ 500), . Integer n represents the number of nodes of the graph G, m represents the number of edges.

The second line contains n space-separated integers xi (1 ≤ xi ≤ 106), where xi represents the value of the i-th node. Consider the graph nodes are numbered from 1 to n.

Each of the next m lines contains three space-separated integers ai, bi, ci (1 ≤ ai < bi ≤ n; 1 ≤ ci ≤ 103), denoting an edge between node ai and bi with value ci. The graph won’t contain multiple edges.

Output
Output a real number denoting the answer, with an absolute or relative error of at most 10 ^- 9.

Hint
In the first sample, you can only choose an empty subgraph, or the subgraph containing only node 1.

In the second sample, choosing the whole graph is optimal.

解题的思路来自：

所以只需找到两个点中密度最大的即可！

代码如下：

#include <iostream>#include <cstdio>using namespace std;int a[505];int main(){    int n,m;    int n1,n2;    double max=0;    int v;    cin>>n>>m;    for(int i=1;i<=n;i++)    {        scanf("%d",&a[i]);    }    if(n==1)    {        cout<<0.000000000000000<<endl;        return 0;     }     for(int j=0;j<m;j++)    {        cin>>n1>>n2>>v;        double n3= (double)(a[n1]+a[n2])/v;        if(n3>max)        {            max=n3;        }    }    printf("%.15lf",max);    return 0;}

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