Construct Binary Tree from Preorder and Inorder Traversal and Sum Root to Leaf Numbers

[anirudhv98]

Completed Trees-2, please review.

[super30admin]

Construct Binary Tree from Inorder and Postorder Traversal (Problem1.cs)

Strengths:

• Excellent use of a dictionary for O(1) lookup of inorder positions
• Clear and concise comments explaining the algorithm
• Proper handling of base case (st > end)
• Correct order of recursive calls (right subtree first, then left) which is essential for postorder processing
• Good variable naming and code organization

Areas for Improvement:

• The solution is already well-optimized. One minor suggestion: you could add inorderLookup.EnsureCapacity(inorder.Length) before the loop to pre-allocate dictionary capacity, but this is a micro-optimization.
• Consider adding null checks for input arrays in a production environment, though for Leetcode-style problems this is typically not required.

The solution demonstrates a solid understanding of tree traversal algorithms and correctly implements the standard approach for this classic problem.

VERDICT: PASS

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Root to Leaf Sum (Problem2.cs)

Strengths:

• The solution correctly implements the DFS algorithm for this problem
• Code is clean, readable, and well-commented
• Good use of early return when a leaf node is found
• Proper handling of edge cases (null root)
• Time and space complexity match the optimal reference solution

Areas for Improvement:

• The solution is functionally equivalent to the reference and doesn't require significant changes
• Minor suggestion: Consider using a more descriptive parameter name than sum in the Helper method to avoid confusion with the built-in Sum method (though this is a very minor concern)

The solution demonstrates a solid understanding of tree traversal and correctly solves the problem.

VERDICT: PASS