Delete Node in a BST

BST中删除节点, 经典算法: 先BST搜到节点, 然后: 1. 如果左子树是空, 返回右子树. 2. 如果右子树是空, 返回左子树. 3. 两个都不是空的, 找到右子树最左的节点, 赋值给root, 然后继续删除右子树root的当前值.

public class Solution {
    public TreeNode deleteNode(TreeNode root, int key) {
        if(root == null)
            return root;
        if(root.val < key)
            root.right = deleteNode(root.right,key);
        else if(root.val > key)
            root.left = deleteNode(root.left, key);
        else{
            if(root.left == null)
                return root.right;
            else if(root.right == null)
                return root.left;
            else{
                TreeNode min = root.right;
                while(min.left != null)
                    min = min.left;
                root.val = min.val;
                root.right = deleteNode(root.right, root.val);
            }
        }
        return root;
    }
}