lca py3

0235_lowest-common-ancestor-of-a-binary-search-tree/python3/solution.py

@@ -0,0 +1,25 @@
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution:
+    def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode':
+        curr = root
+        
+        while curr:
+            # Both p and q can be found in right subtree so move
+            # curr there
+            if p.val > curr.val and q.val > curr.val:
+                curr = curr.right
+            # Both p and q can be found in left subtree so move
+            # curr there
+            elif p.val < curr.val and q.val < curr.val:
+                curr = curr.left
+            # If above cases fail, that means we are already at a `curr`
+            # where p exists in one side and q exists on another side so 
+            # that must mean `curr` is the LCA
+            else:
+                return curr