从二叉搜索树中删除元素

Question

I am currently writing a method that removes a given value from a binary search tree. However when I call it, it deletes the said value but then duplicates every other value. I have no idea why. Please tell me what is wrong. There are two methods, one that find the elements, and the other that deletes it. Here is the one that finds that element...

public static TreeNode delete(TreeNode t, Comparable x, TreeDisplay display)
{
    if( x.compareTo(t.getValue()) > 0)
        {
             display.visit(t);

             t.setRight(delete( t.getRight(), x, display));

    }
    else if ( x.compareTo(t.getValue()) < 0)
    {
        display.visit(t);

        t.setLeft(delete(t.getLeft(), x, display));
    }
    else
    {
        t = deleteNode(t, display);
    }

    return t;

This is the method that deletes the value

private static TreeNode deleteNode(TreeNode t, TreeDisplay display)
  {

    if (t.getRight()!=null)
    {
        TreeNode right = t.getRight();
        TreeNode max = (TreeNode)TreeUtil.leftmost(right);
        TreeNode previous = null;
        while ( right.getLeft()!=null&&right.getLeft().getLeft()!=null)
        {
            right = right.getLeft();
        }
        t.setValue(max.getValue());
        if ( max.getRight()==null)
        {
            right.setLeft(null);
        }
        else
        {
            right.setLeft(max.getRight());
        }
    }
    else if (t.getLeft() !=null)
    {
        TreeNode left = t.getLeft();
        TreeNode max = (TreeNode)TreeUtil.rightmost(left);
        while(left.getRight()!=null &&left.getRight().getRight()!=null)
        {
            left = left.getRight();
        }
        t.setValue(max.getValue());
        if ( max.getLeft()==null)
        {
            left.setRight(null);
        }
        else
        {
            left.setRight(max.getLeft());
        }
    }
    else
    {
        t = null;
    }
    return t;
}

Thanks in advance!

Answer 1

...it deletes the said value but then duplicates every other value. I have no idea why. Please tell me what is wrong.

It's because you're returning the deleted node from deleteNode() , and in the first method delete() , your calls to setRight() and setLeft() are setting every traversed element to the deleted element as the recursion unwinds back up the tree.