Week 15: 572. Subtree of Another Tree Solution

Author: doh6077

subtree-of-another-tree/doh6077.py

@@ -0,0 +1,43 @@
+from collections import deque
+from typing import Optional
+
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+# 572. Subtree of Another Tree
+# https://leetcode.com/problems/subtree-of-another-tree/description/
+class Solution:
+    def isSubtree(self, root: Optional[TreeNode], subRoot: Optional[TreeNode]) -> bool:
+        # Use BFS => Queue 
+        # Edge cases
+        if subRoot is None:
+            return True
+        if root is None:
+            return False
+
+        def helper(node: Optional[TreeNode], subNode: Optional[TreeNode]) -> bool:
+            if node is None and subNode is None:
+                return True
+            if node is None or subNode is None:
+                return False
+            if node.val != subNode.val:
+                return False
+            return helper(node.left, subNode.left) and helper(node.right, subNode.right)
+
+        q = deque([root])
+
+        while q:
+            curr = q.popleft()
+
+            # Only attempt full compare when root values match
+            if curr.val == subRoot.val and helper(curr, subRoot):
+                return True
+
+            if curr.left:
+                q.append(curr.left)
+            if curr.right:
+                q.append(curr.right)
+
+        return False