// @Title: 删除二叉搜索树中的节点 (Delete Node in a BST)
// @Author: qisiii
// @Date: 2024-09-16 17:32:48
// @Runtime: 0 ms
// @Memory: 44.9 MB
// @comment: 
// @flag: 
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 * int val;
 * TreeNode left;
 * TreeNode right;
 * TreeNode() {}
 * TreeNode(int val) { this.val = val; }
 * TreeNode(int val, TreeNode left, TreeNode right) {
 * this.val = val;
 * this.left = left;
 * this.right = right;
 * }
 * }
 */
class Solution {
    TreeNode parent;

    public TreeNode deleteNode(TreeNode root, int key) {
        if(root==null){
            return null;
        }
        if (root.val == key) {
            //左右任意节点为空
            if (root.left == null || root.right == null) {
                return root.left == null ? root.right : root.left;
            }else{
                TreeNode cur=root.right;
                while(cur.left!=null){
                    cur=cur.left;
                }
                cur.left=root.left;
                return root.right;
            }
        } else if (root.val > key) {
            root.left = deleteNode(root.left, key);
        } else {
            root.right = deleteNode(root.right, key);
        }
        return root;
    }
}