Leetcode subtree of another tree

tree.md

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+# Binary tree
+
++ [Subtree of Another Tree](#subtree-of-another-tree)
+
+## Subtree of Another Tree
+
+https://leetcode.com/problems/subtree-of-another-tree/
+
+```python
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution(object):
+    def isSubtree(self, s, t):
+        def traverse_tree(node):
+            if not node:
+                return None
+            return "#{} {} {}".format(node.val, traverse_tree(node.left), traverse_tree(node.right))
+
+        return traverse_tree(t) in traverse_tree(s)
+
+```