[LeetCode&Python] Problem 669. Trim a Binary Search Tree
Given a binary search tree and the lowest and highest boundaries as L
and R
, trim the tree so that all its elements lies in [L, R]
(R >= L). You might need to change the root of the tree, so the result should return the new root of the trimmed binary search tree.
Example 1:
Input: 1 / \ 0 2 L = 1 R = 2 Output: 1 \ 2
Example 2:
Input: 3 / \ 0 4 \ 2 / 1 L = 1 R = 3 Output: 3 / 2 / 1
# 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, L, R): """ :type root: TreeNode :type L: int :type R: int :rtype: TreeNode """ if root==None: return root if R<root.val: return self.trimBST(root.left,L,R) if L>root.val: return self.trimBST(root.right,L,R) root.left=self.trimBST(root.left,L,R) root.right=self.trimBST(root.right,L,R) return root