Sync LeetCode submission Runtime - 1 ms (20.77%), Memory - 19.5 MB (63.53%)

Author: jimit105

0270-closest-binary-search-tree-value/solution.py

@@ -1,16 +1,23 @@
-# Approach 1 - Recursive Inorder + Linear search, O(N) time
+# Approach 3: Binary Search
+
+# h = height of the tree
+# Time: O(h)
+# Space: O(1)
 
 # Definition for a binary tree node.
 # class TreeNode:
 #     def __init__(self, val=0, left=None, right=None):
 #         self.val = val
 #         self.left = left
 #         self.right = right
+
 class Solution:
     def closestValue(self, root: Optional[TreeNode], target: float) -> int:
-        
-        def inorder(r: TreeNode):
-            return inorder(r.left) + [r.val] + inorder(r.right) if r else []
-        
-        return min(inorder(root), key=lambda x: abs(x-target))
+        closest = root.val
+
+        while root:
+            closest = min(root.val, closest, key = lambda x: (abs(target - x), x))
+            root = root.left if target < root.val else root.right
+
+        return closest