for(int k = 1;k<=n;k++)
    for(int i = 1;i<=k-1;i++){
        for(int j = i+1;k<=k-1;j++){
            answer = min(ans,dis[i][j]+g[j][k]+g[k][i]);
        }
        for(int i = 1;i<=n;i++)
            for(int j = 1;j<=n;j++){
                dis[i][j] = min(dis[i][j],dis[i][k]+dis[k][j]);//老套路
            }
    }