Create 236-Lowest-Common-Ancestor-of-a-Binary-Tree.py

Author: neetcode-gh

236-Lowest-Common-Ancestor-of-a-Binary-Tree.py

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+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution:
+    res = None
+    def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode':
+        if not root or not p or not q: return None
+        
+        def search(root, p, q):
+            if not root: return False
+            mid = left = right = False
+            if root.val == p.val or root.val == q.val: 
+                mid = True
+            
+            left = search(root.left, p, q)
+            right = search(root.right, p, q)
+            if mid:
+                if left or right:
+                    self.res = root
+            elif left and right:
+                self.res = root
+            return mid or left or right
+            
+        search(root, p, q)
+        return self.res