resolve lc 652

Author: jsgoller1

leetcode/652-find-duplicate-subtrees/solution.py renamed to leetcode/652-find-duplicate-subtrees/1.py

@@ -0,0 +1,26 @@
+# 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 findDuplicateSubtrees(self, root: TreeNode) -> List[TreeNode]:
+        self.subtrees = set()
+        self.known_duplicates = set()
+        self.duplicate_nodes = set()
+
+        def dfs(node):
+            if not node:
+                return ""
+            sig = f"{node.val},{dfs(node.left)},{dfs(node.right)}"
+            if sig not in self.subtrees:
+                self.subtrees.add(sig)
+            elif sig not in self.known_duplicates:
+                self.known_duplicates.add(sig)
+                self.duplicate_nodes.add(node)
+            return sig
+        dfs(root)
+        return list(self.duplicate_nodes)