Sort Colors, 3Sum and Container With Most Water

[anirudhv98]

Completed Two-Pointers-1, please review.

[super30admin]

Arrange Colors (Problem1.cs)

Strengths:

• Correct implementation of the Dutch National Flag algorithm
• Clean, readable code with descriptive variable names
• Good separation of concerns with a dedicated Swap method
• Includes helpful comments explaining complexity upfront
• Matches the reference solution's approach and efficiency

Areas for minor improvement:

• The comments could be slightly more detailed (e.g., explaining the three-pointer invariants)
• Could add input validation for edge cases (though not strictly necessary given constraints)
• Consider adding XML documentation comments for the public method

Overall, this is a solid implementation that demonstrates good understanding of the problem and algorithm.

VERDICT: PASS

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3 sum (Problem2.cs)

Strengths:

1. Excellent use of the two-pointer technique, which is the optimal approach for this problem
2. Proper handling of duplicates at all three levels (outer loop and inner pointers)
3. Clean, readable code with good variable naming
4. Significant improvement over the brute-force O(n³) approach

Areas for minor improvement:

1. The comment "Time Complexity: O(n)" is incorrect - it should be O(n²) since the two-pointer search is still linear for each outer iteration
2. Could add a comment explaining why we sort the array first
3. The space complexity comment mentions O(n) but doesn't clarify that this is for the result storage in worst case

Overall, this is a solid, efficient solution that demonstrates good understanding of the two-pointer technique and duplicate handling.

VERDICT: PASS

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Container With Most Water (Problem3.cs)

Strengths:

• Excellent implementation of the two-pointer technique
• Clear and descriptive variable naming
• Comprehensive comments including time/space complexity analysis
• Correct handling of edge cases (equal heights, single movement per iteration)
• The solution passes all test cases on Leetcode

Areas for Improvement:

• The while condition could be low < high instead of low <= high since when low == high, the area calculation would yield zero (width is zero), making no difference to the result. This is a minor optimization but more idiomatic.
• Consider adding a brief comment explaining why we move the pointer pointing to the shorter line (because moving the taller line can only decrease the width and potentially decrease the height, never increasing the area).

VERDICT: PASS