669_trim_a_binary_search_tree.py

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def trimBST(self, root: TreeNode, L: int, R: int) -> TreeNode:
        if root == None:
            return None
        else:
            if root.val >= L and root.val <= R:
                root.left = self.trimBST(root.left, L, R)
                root.right = self.trimBST(root.right, L, R)
                return root
            elif root.val < L:
                return self.trimBST(root.right, L, R)
            else:
                return self.trimBST(root.left, L, R)

'''
    This is my personal record of solving Leetcode Problems. 
    If you have any questions, please discuss them in [Issues](https://github.com/mengxinayan/leetcode/issues).
    Copyright (C) 2020-2022  mengxinayan

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
'''