最少时间内数组的连续子阵列的总和

This is my code:

这是我的代码:

long sum(int[] arr) {
    long sum=0;
    int j,k;
    long sumtoadd;
    for (int i = 0; i < arr.length; i++)
    {
        for (j = i; j < arr.length; j++)
        {
            sumtoadd = 0;
            for (k = i; k <= j; k++)
            {
                sumtoadd = sumtoadd + arr[k];
            }
            sum = sumtoadd + sum;
        }
    }
    return sum;
}
long sum(int[] arr