Strengths:

• Excellent implementation of efficient algorithms for all three problems.
• Clear and concise comments explaining the approach.
• Proper handling of edge cases and boundary conditions.
• Good use of variable naming and code structure.

Areas for Improvement:

• While the comments are good, adding a brief problem description at the top of each file would make it even clearer.
• In problem1.java, the space complexity comment could be more precise by mentioning that the output array is not considered in the space complexity calculation (which is already done, but could be emphasized).
• In problem3.java, the condition checks (if (top <= bottom) and if (left <= right)) are excellent for avoiding duplicates, but a brief comment explaining why they are needed would be helpful for readers.

Strengths:

• The student demonstrates a strong understanding of time and space complexity, providing optimal solutions for each problem.
• The code is clean, well-commented, and easy to follow.
• The student handles edge cases and boundary conditions effectively, as seen in problem2 and problem3.

Areas for Improvement:

• While the comments are helpful, they could be slightly more detailed in explaining the rationale behind certain steps, especially for problem2 where direction changes are involved.
• In problem3, the student could add a brief comment explaining why the additional checks (if (top <= bottom) and if (left <= right)) are necessary to avoid duplicates.