leetcode450. 删除二叉搜索树中的节点(java详解版)

class Solution {
    
    public TreeNode deleteNode(TreeNode root, int key) {
        if (root == null) return null;

        if (root.val > key) root.left = deleteNode(root.left,key);
        else if (root.val < key) root.right = deleteNode(root.right,key);
        else {
                 System.out.println("wyj");
                if (root.left == null && root.right == null) {
                    root = null;
                    return root;
                } else if (root.left != null && root.right == null) {
                    root = root.left;
                    return  root; 
                } else if (root.right != null && root.left == null) {
                    root = root.right;
                    return root;
                } else {
                    TreeNode temp = root.right;
                    while (temp.left != null) {
                        temp = temp.left;
                    }
                    temp.left = root.left;
                    root = root.right;
                    
                    System.out.println("wyj");
                    return root;


                }
        }
//  System.out.println("wyj");
        return root;
    }
}