two-pointers-2

[joshyoon92]

No description provided.

[super30admin]

Merge Sorted Array (MergeSorted.java)

Strengths:

• Correctly implements the merge algorithm with proper pointer management
• Good use of in-place merging to achieve O(1) space complexity
• Clean and readable code structure
• Handles edge cases properly (when m=0 or n=0)

Areas for Improvement:

• Consider renaming variables to be more descriptive (e.g., p1 and p2 instead of left and i to match common conventions)
• The condition while (i>=0 && left>=0) in the first loop could be simplified to just while (left >= 0) since the second while loop handles remaining nums2 elements. However, this is a minor stylistic choice.
• Adding comments explaining the algorithm would improve readability for others reading the code

VERDICT: PASS

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Search a 2D Matrix II (RemoveDup.java)

1. Wrong Problem: The submitted solution solves a completely different problem. The code removes duplicates from a sorted array allowing at most 2 occurrences, not searching for a target in a 2D matrix.

2. Wrong Language: The reference solution is in C++, but using Java is acceptable. However, the student should ensure the solution matches the problem.

3. For the actual problem (Search a 2D Matrix II): The reference solution uses binary search on each row, achieving O(m log n) time. A more optimal approach would be to start from the top-right corner and eliminate either a row or column at each step, achieving O(m + n) time.

4. If this were the RemoveDup problem: The solution is well-structured with clear variable naming (slow, fast, count). The logic correctly handles the at-most-2-duplicates requirement. However, the code could benefit from comments explaining the two-pointer technique.

VERDICT: NEEDS_IMPROVEMENT

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Remove Duplicates from Sorted Array II (Search2D.java)

1. Wrong Problem: You submitted code for "Search 2D Matrix II" instead of "Remove Duplicates from Sorted Array II". Please ensure you are working on the correct problem assignment.

2. Syntax Error: The variable matrix is used but never defined. The method parameter is m, so you should use m[row][col] instead of matrix[row][col].

3. Missing Solution: There is no attempt to solve the duplicate removal problem. The correct approach would use a two-pointer technique where you track the count of consecutive duplicates and only write elements that appear at most twice.

4. Code Structure: If you were to solve the correct problem, your code should:

   • Use two pointers (slow and fast)
   • Track the count of consecutive duplicate elements
   • Only copy elements to the slow pointer when count ≤ 2
   • Return the length of the modified array

Please resubmit a solution for the correct problem "Remove Duplicates from Sorted Array II".

VERDICT: NEEDS_IMPROVEMENT