Binary Search(Java)(递归)

public static int rank(int[] array, int k, int front, int rear)
{
    if(front > rear)
        return -1;
        
    int mid = front + (rear - front) / 2;
    if(k == array[mid])
        return mid;
    else if(k > array[mid])
        return rank(array, k, mid + 1, rear);
    else 
        return rank(array, k, front, mid - 1);
}