二进制搜索树递归删除

Question

I'm working on Binary Search Trees, and currently working on recursive delete method. I have a bug in my code; it deletes nodes with no children and with one-child. Problem arises when trying to delete node with two children. (Point of reference - I am replacing deleted node with smallest node in Right Subtree)

My code is:

//Driver
public void delete (String val){
root = delete(root, val);
}

//Recursive Delete Method   
private static StringNode delete(StringNode node, String v){
        StringNode temp;
        if(node == null){
            return null;
        }
        if(v.compareTo(node.getString()) < 0){
            node.setLeft(delete(node.getLeft(), v));
        }
        else if(v.compareTo(node.getString()) > 0){
            node.setRight(delete(node.getRight(), v));
        }
        else{
            if(node.getLeft() == null){
                node = node.getRight();
            }
            else if(node.getRight() == null){
                node = node.getLeft();
            }
            else{
                node = node.getRight();
                while(node.getLeft() != null){
                    node = node.getLeft();
                }
                node.setRight(delete(node, node.getString()));
            }
        }
        return node;
    }

I have debugged and see that I lose a child when re-connecting the nodes after deletion. But I don't know how to correct in my code.

Answer 1

I figured out the bug. I separated the delete method into delete and deleteNode methods. Worked out.