Leetcode Problem 652. Find Duplicate Subtrees

652. Find Duplicate Subtrees

Leetcode Solutions

An Optimized Approach Using Serialization and Hashing

  1. Define a helper function serialize that takes a node and performs a post-order traversal to serialize the subtree rooted at that node.
  2. In serialize, if the node is None, return a unique marker (e.g., #).
  3. Recursively serialize the left and right children of the node.
  4. Combine the serialized left subtree, node value, and serialized right subtree into a string.
  5. Check if the serialized string is already in the hash map. If it is and the count is 1, add the node to the result list.
  6. Increment the count of the serialized string in the hash map.
  7. Return the serialized string.
  8. Call serialize on the root node to start the process.
  9. Return the result list containing the roots of all duplicate subtrees.
UML Thumbnail

A String Representation Approach

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