38 lines
1.2 KiB
Python
38 lines
1.2 KiB
Python
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# Time: O(N)
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# Space: O(N) due to call stack
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# Definition for a binary tree node.
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# class TreeNode:
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# def __init__(self, val=0, left=None, right=None):
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# self.val = val
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# self.left = left
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# self.right = right
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class Solution:
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def trimBST(self, root: Optional[TreeNode], low: int, high: int) -> Optional[TreeNode]:
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# Recursion approach
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def trim(node):
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# Base case
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if node is None:
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return None
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if node.val < low:
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# Cause everything to the left will be
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# less than `low` and hence trimmed
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return trim(node.right)
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elif node.val > high:
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# Cause everything to the right will be
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# greater than `high` and hence trimmed
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return trim(node.left)
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else:
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# `node.val` is between [low, high] so
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# just need to trim their left and right
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# subtrees
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node.left = trim(node.left)
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node.right = trim(node.right)
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return node
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return trim(root)
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