7-36 社交网络图中结点的“重要性”计算 (30分)-floyd最短路径

#include <iostream>
#include <cstdio>
#include <iomanip>
#define infinity 65535
using namespace std;
int D[10001][10001];//储存最短路径
    int N;
    long int M;
int main()
{
    
    cin >> N >> M;
    for(int i=1;i<=N;i++)
        for (int j = 1; j <= N; j++)
        {
            D[i][j] = infinity;
        }
    for (int i = 0; i < M; i++) 
    {
        int a, b;
        cin >> a >> b;
        D[a][b]= D[b][a] = 1;
    }
//floyd算法
    for(int k=1;k<=N;k++)
        for(int i=1;i<=N;i++)
            for (int j = 1; j <= N;j++)
            {
                if (i == j || i == k || j == k)continue;
                if (D[i][k] + D[k][j] < D[i][j])
                {
                    D[i][j] =D[j][i]= D[i][k] + D[k][j];
                }
            }
    int n;
    cin >> n;
    int flag=0;
    for (int i = 0; i < n; i++)
    {
        int x;
        double sum=0;
        cin >> x;
            for (int k = 1; k <= N; k++)
            {
                if(x==k)continue;
                if(flag==1)break;
                if(D[x][k]==infinity)
                {
                   flag =1;
                   break;
                }
                else sum += D[x][k];
            }
            if(flag)//如果是非连通图
            cout << setprecision(2) << fixed << "Cc(" << x << ")=" << "0.00"<<endl;
            else cout << setprecision(2) << fixed << "Cc(" << x << ")=" << (N - 1.0) / sum <<endl;
    }
    return 0;
}