Leaf nodes of preordered BST given as array

Question

Here is my program to get leaf nodes of BST given as array in pre-order. The program somehow just prints the first leaf and not all. I have tried finding the bug but wasn't able to. here is the program:

     //method
    public static boolean isLeaf(int pre[], int i, int n,
        int min, int max)
         {    
           if (i >= n) 
            return false;

           if(pre[i] > min && pre[i] < max) {
            i++;

            boolean left = isLeaf(pre, i, n, min, pre[i-1]);

            boolean right = isLeaf(pre, i, n, pre[i-1], max);

            if (!right && !left) 
              System.out.println(pre[i-1] );

            return true;
     }


     return false;
      }



    //Test case:
     public static void main(String[] args){
    int preorder[] = { 890, 325, 290, 530, 965 };
    int n = preorder.length;
    int i=0;
    isLeaf( preorder,  i,  n,
            Integer.MIN_VALUE, Integer.MAX_VALUE); 
     }

     //it just prints 290, it should print 290, 530, 965 instead 

Answer 1

I'm sure this can be cleaned up a bit. And I'm not 100% certain it catches all the corner cases, but here's my attempt. This assumes all elements are unique and strictly on the open range (Integer.MIN_VALUE, Integer.MAX_VALUE) .

public class bst
{
    public static void print_leaves(int[] preorder)
    {
        if (preorder.length == 1)
        {
            System.out.println(preorder[0]);
        }
        else if (preorder.length > 1)
        {
            print_leaves(preorder, 0, Integer.MIN_VALUE, Integer.MAX_VALUE);
        }
    }

    public static boolean is_in_range(int min, int v, int max)
    {
        return min < v && v < max;
    }

    public static int print_leaves(int[] preorder, int i, int min, int max)
    {
        boolean in_range = is_in_range(min, preorder[i], max);
        if (i > 0 && (i == preorder.length-1 || !in_range))
        {
            if (!in_range) System.out.println(preorder[i-1]);
            if (i == preorder.length - 1) System.out.println(preorder[i]);
            return i;
        }

        boolean b = preorder[i+1] > preorder[i];
        int next = print_leaves(preorder, i+1, b ? preorder[i] : min, b ? max : preorder[i]);
        if (next == preorder.length-1 || !is_in_range(min, preorder[next], max))
        {
            return next;
        } 
        return print_leaves(preorder, next, min, max);
    }

    public static void main(String[] argv)
    {
        int[] preorder1 = { 890, 325, 290, 530, 965 };
        int[] preorder2 = { 100, 50, 25, 30, 29, 28, 75, 80, 200, 150, 250 };
        int[] preorder3 = { 0 };
        int[] preorder4 = { 100, 0, 200 };
        int[] preorder5 = { 100, 200 };
        int[] preorder6 = { 100, 50 };
        print_leaves(preorder1);
        System.out.println();
        print_leaves(preorder2);
        System.out.println();
        print_leaves(preorder3);
        System.out.println();
        print_leaves(preorder4);
        System.out.println();
        print_leaves(preorder5);
        System.out.println();
        print_leaves(preorder6);
    }
}

Yields the following output:

290
530
965

28
80
150
250

0

0
200

200

50