Completed Arrays 2

[sanjoli97]

No description provided.

[super30admin]

Disappeared Numbers (FindDisappearedNumbers.java)

Strengths:

• Correctly implements the O(n) time, O(1) space solution using in-place array modification
• Clean, readable code with good variable names
• Excellent time complexity (O(n)) compared to the reference solution's O(n²)
• Good use of comments explaining the approach
• Properly handles edge cases like duplicate values

Areas for Improvement:

• The comment "TC - O(n)" is slightly imprecise; technically this is O(2n) = O(n), but the first pass is O(n) and second pass is O(n), so overall O(n)
• Could add a brief comment explaining why we use Math.abs() - to handle cases where we've already negated the value

Comparison to Reference:

• The student's solution is significantly more efficient (O(n) vs O(n²))
• The student achieves the follow-up requirement that the reference solution does not

VERDICT: PASS

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max and min (MinAndMax.java)

Strengths:

• Correctly implements the optimal pairwise comparison algorithm
• Excellent comment explaining time complexity O(3n/2)
• Clean, readable code with good variable naming
• Properly handles edge cases (odd/even array lengths)
• Well-documented logic flow

Areas for Improvement:

• Consider returning int[] instead of ArrayList<Integer> for better performance (avoids autoboxing and wrapper object creation)
• The while condition i < arr.length - 1 works but could be simplified to i < arr.length since the pair comparison naturally stops at the last valid pair
• Could add a null check for robustness in production code

VERDICT: PASS

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Life Game (GameOfLife.java)

Strengths:

• Good use of in-place modification technique with marker values
• Clear separation between logic and cleanup phases
• Well-documented with explanatory comments
• Proper boundary checking in the counting method

Areas for Improvement:

• Critical Bug: The condition board[nr][nc] > 0 in countLiveCells is incorrect. It counts cells with value 2 as live, but these are actually dead cells (1→0 transitions). Should use board[nr][nc] == 1 || board[nr][nc] == 2 like the reference solution.
• Incorrect Time Complexity Comment: The comment states O(n) but should be O(m*n) for a 2D grid.
• Edge Case: When count is exactly 3, the code correctly handles birth for dead cells and survival for live cells. However, the counting bug could cause cascading errors in complex configurations.

VERDICT: NEEDS_IMPROVEMENT