Path Sum II and Symmetric Tree

[anirudhv98]

Completed Trees-3, please review.

[super30admin]

Root-to-leaf Sum II (Problem1.cs)

Strengths:

• Clean implementation of the backtracking DFS pattern
• Well-documented code with clear comments
• Proper use of C# conventions (IList interface, private fields)
• Correct handling of edge cases (empty tree, leaf nodes)
• Good variable naming that makes the code self-explanatory

Areas for Improvement:

• The time complexity claim of O(n) is slightly misleading; while each node is visited once, the path copying in worst case makes it O(n²). Consider clarifying this in comments.
• Could consider using List<int> path as a parameter passed by value to avoid explicit backtracking, though current approach is fine.

VERDICT: PASS

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Mirror Image of Itself Tree (Problem2.cs)

Strengths:

• Correct recursive logic that properly compares mirrored nodes
• Good use of early returns to handle null cases efficiently
• Clean, readable code with helpful comments
• Proper separation of concerns with a dedicated helper function

Areas for Improvement:

• Space complexity claim is incorrect - recursive solutions inherently use O(h) stack space, not O(1). This should be O(h) where h is tree height.
• Could simplify the null checking logic using: if (a == null || b == null) return a == null && b == null;
• Consider adding the iterative approach as mentioned in the follow-up to demonstrate comprehensive understanding

VERDICT: PASS