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 is None:
return None
if root.val<L:
return self.trimBST(root.right,L,R)
if root.val>R:
return self.trimBST(root.left,L,R)
root.left = self.trimBST(root.left,L,R)
root.right = self.trimBST(root.right,L,R)
return root