Apr 04

Author: siddydutta

2025-04-April-LeetCoding-Challenge/Lowest Common Ancestor of Deepest Leaves.py

@@ -0,0 +1,54 @@
+from typing import Optional
+
+
+# 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 lcaDeepestLeaves(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
+
+        def postorder(node: Optional[TreeNode]) -> tuple[int, Optional[TreeNode]]:
+            if node is None:
+                return 0, None
+
+            left_depth, left_lca = postorder(node.left)
+            right_depth, right_lca = postorder(node.right)
+
+            if left_depth > right_depth:
+                return left_depth + 1, left_lca
+            elif right_depth > left_depth:
+                return right_depth + 1, right_lca
+            return left_depth + 1, node
+
+        return postorder(root)[1]
+
+
+def main():
+    root = TreeNode(3)
+    root.left = TreeNode(5)
+    root.right = TreeNode(1)
+    root.left.left = TreeNode(6)
+    root.left.right = TreeNode(2)
+    root.left.right.left = TreeNode(7)
+    root.left.right.right = TreeNode(4)
+    root.right.left = TreeNode(0)
+    root.right.right = TreeNode(8)
+    assert Solution().lcaDeepestLeaves(root) == root.left.right
+
+    root = TreeNode(1)
+    assert Solution().lcaDeepestLeaves(root) == root
+
+    root = TreeNode(0)
+    root.left = TreeNode(1)
+    root.right = TreeNode(3)
+    root.left.right = TreeNode(2)
+    assert Solution().lcaDeepestLeaves(root) == root.left.right
+
+
+if __name__ == '__main__':
+    main()

2025-04-April-LeetCoding-Challenge/README.md

@@ -7,7 +7,7 @@
 | April 01 | [2140. Solving Questions With Brainpower](https://leetcode.com/problems/solving-questions-with-brainpower/) | Medium | Solved |
 | April 02 | [2873. Maximum Value of an Ordered Triplet I](https://leetcode.com/problems/maximum-value-of-an-ordered-triplet-i/) | Easy | Solved |
 | April 03 | [2874. Maximum Value of an Ordered Triplet II](https://leetcode.com/problems/maximum-value-of-an-ordered-triplet-ii/) | Medium | Solved |
-| April 04 | []() |  |  |
+| April 04 | [1123. Lowest Common Ancestor of Deepest Leaves](https://leetcode.com/problems/lowest-common-ancestor-of-deepest-leaves/) | Medium | Solved |
 | April 05 | []() |  |  |
 | April 06 | []() |  |  |
 | April 07 | []() |  |  |
@@ -40,5 +40,5 @@
 | Level  | Problems | Solved | Unsolved |
 | ---    | --- | --- | --- |
 | Easy   | 1 | 1 | 0 |
-| Medium | 2 | 2 | 0 |
+| Medium | 3 | 3 | 0 |
 | Hard   | 0 | 0 | 0 |