noi 2007 社交网络 最短路

题意：

大水题一道

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
using namespace std;
#define MAXN 101
int map[MAXN][MAXN];
long long path[MAXN][MAXN];
int c[MAXN][MAXN][MAXN];
double ans[MAXN];
int n,m;
void solve()
{
    memset(ans,0,sizeof(ans));
    int i,j,k;
    for(k=1;k<=n;k++)
        for(i=1;i<=n;i++)
            for(j=1;j<=n;j++)
                if(i!=j&&j!=k&&k!=i)
                {
                    if(map[i][k]+map[k][j]==map[i][j])
                        ans[k]+=(double)path[i][k]*path[k][j]/path[i][j];
                }
    for(i=1;i<=n;i++)
        printf("%.3lf\n",ans[i]);
}
 
void floyd()
{
    int i,j,k;
    for(k=1;k<=n;k++)
        for(i=1;i<=n;i++)
            for(j=1;j<=n;j++)
                if(i!=j&&j!=k&&i!=k)
                {
                    if(map[i][k]+map[k][j]<map[i][j])
                    {
                        map[i][j]=map[i][k]+map[k][j];
                        path[i][j]=path[i][k]*path[k][j];
                    }
                    else if(map[i][k]+map[k][j]==map[i][j])
                        path[i][j]+=path[i][k]*path[k][j];
                }
}
int main()
{
    memset(path,0,sizeof(path));
    memset(map,0x3f,sizeof(map));
    int x,y,z;
    scanf("%d%d",&n,&m);
    int i;
    for(i=1;i<=m;i++)
    {
        scanf("%d%d%d",&x,&y,&z);
        map[x][y]=map[y][x]=z;
        path[x][y]=path[y][x]=1;
    }
    floyd();
    solve();
    return 0;
}