Solved Array-2

[vvkumaryadla]

Solved Array-2

[super30admin]

Disappeared Numbers (Problem1.java)

Strengths:

• Correctly implements the O(n) time and O(1) space solution using in-place marking
• Properly handles potential negative values with Math.abs()
• Includes restoration of the original array (good practice for not mutating input)
• Clear comments explaining the algorithm logic
• Good variable naming and code structure

Areas for Improvement:

• The third loop to restore the array is technically unnecessary since the problem doesn't require preserving the input array, but it's good defensive programming
• Could add input validation for edge cases (though constraints guarantee valid input)
• The comment could be slightly clearer about why we use negative marking

Comparison to Reference:

• The student's solution is significantly better than the reference O(n²) brute force solution
• Student achieves O(n) time complexity vs O(n²) in reference
• Both achieve O(1) auxiliary space complexity

VERDICT: PASS

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max and min (Problem2.java)

Strengths:

• Correctly implements the pairwise comparison technique
• Clear and informative comments explaining the algorithm and comparison counts
• Good variable naming and code organization
• Handles edge cases (empty array would be an issue, but the problem implies N≥1)
• Efficient with O(n) time and O(1) space complexity

Areas for Improvement:

• The solution doesn't handle the edge case of an empty array (would throw ArrayIndexOutOfBoundsException)
• For even-length arrays, initializing min and max by comparing the first pair (like the reference solution) could save comparisons in the loop
• The return type (ArrayList) differs from the reference solution (int[]), though both are valid approaches

VERDICT: PASS

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Life Game (Problem3.java)

Strengths:

• Clean separation of concerns with a dedicated helper method getLiveCellCount()
• Clear comments explaining the temporary values (2 and 3)
• Good variable naming (e.g., liveCellCount, totalRows, totalColumns)
• Correctly handles boundary conditions
• Properly counts neighbors including cells marked with temporary values

Areas for Improvement:

• The dirs array could be declared as a static final class constant to avoid recreating it for each cell (though Java may optimize this)
• Consider combining the two final passes into one loop for slightly better performance
• The method signature could use int[][] board without the redundant m and n parameters since they can be derived from the board array

Overall, this is a solid solution that correctly implements the Game of Life in-place algorithm.

VERDICT: PASS