[IMP] Trees-2

[amitmittal117]

No description provided.

[super30admin]

Your solution for constructing the binary tree from inorder and postorder traversals is correct and efficient. Well done! Here are a few points to consider for improvement:

• While using instance variables (self.hashmap and self.idx) is acceptable for this problem, it's important to note that this approach makes the solution stateful and not thread-safe. In a production environment, you might want to avoid using instance variables for recursive helper functions to make the function reentrant. Alternatively, you could pass the necessary state as parameters or use a nested function with nonlocal variables (in Python) to avoid storing state in the instance. However, for Leetcode, this is fine.

• The print statements (print(self.hashmap) and print(rootval) are useful for debugging but should be removed in production code to avoid unnecessary output.

• The code structure is clear, but you might consider adding docstrings to the helper function to explain its parameters and purpose.

• For the second problem (sum-root-to-leaf-numbers) that you included in the same file, it's generally better to separate solutions for different problems into different files. This helps in maintaining clarity and avoids confusion.

Overall, your solution is excellent. Keep up the good work!

[super30admin]

Your solutions for both problems are well-implemented and demonstrate a good understanding of tree traversals and recursion. Here are some specific points:

Strengths:

• You correctly used a hashmap to store inorder indices for efficient lookup in the tree construction problem.
• The recursive helper functions are appropriately designed.
• The time and space complexities are optimal for both solutions.

Areas for Improvement:

• In the tree construction solution, remove the print statements (print(self.hashmap) and print(rootval)) as they are debugging aids and not needed in the final code. They can slow down the solution and are not professional in production code.
• For the tree construction solution, consider using local variables or passing parameters instead of class variables for hashmap and idx to avoid potential issues in multiple instances, but this is acceptable in the context of Leetcode where the solution is run once per instance.
• In the sum root to leaf numbers solution, you could avoid using a class variable total by having the helper function return the sum recursively, but your approach is clear and correct.

Overall, your code is clean and efficient. Keep up the good work!