Binary Search - Search in Rotated Sorted Array

[MohithN02]

Binary Search - Search in Rotated Sorted Array

[super30admin]

Search in Rotated Sorted Array (SearchInRotatedSortedArray.java)

Excellent work! Your solution correctly implements the binary search approach for searching in a rotated sorted array. Here are some observations:

Strengths:

1. Correct algorithm: You correctly identified the key insight - determining which half is sorted and then narrowing the search range based on whether the target falls within that sorted range.
2. Optimal complexity: Both time (O(log n)) and space (O(1)) complexities are optimal.
3. Clean code: The code is readable and well-commented.
4. Proper edge case handling: The conditions nums[low] <= nums[mid] and the boundary checks are correctly handled.

Minor suggestions for improvement:

1. Space Complexity comment: You left the Space Complexity comment empty. It's good practice to fill this in (O(1) in this case).
2. Consider adding inline comments within the code to explain the logic of each branch, which would make it even more readable for others.
3. Class naming convention: In Java, class names typically follow PascalCase, which you have done correctly with SearchInRotatedSortedArray.

Overall, this is a solid implementation that demonstrates a clear understanding of the problem and the binary search technique.

VERDICT: PASS

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Search in a Sorted Array of Unknown Size (SearchInInfiniteSortedArray.java)

The student's solution is essentially identical to the reference solution in terms of algorithm and structure. Let me analyze it:

1. Correctness: The solution correctly implements the two-phase approach:

   • First phase: Exponential search to find the bounds where the target could exist
   • Second phase: Binary search within those bounds
   • The logic is sound and handles all edge cases properly.

2. Time Complexity: O(log n) - matches the reference solution. The exponential search takes O(log n) time to find the bounds, and the binary search also takes O(log n) time.

3. Space Complexity: O(1) - matches the reference solution. Only a constant number of variables are used.

4. Code Quality:

   • The code is well-structured and readable
   • Variable names are clear (low, high, mid)
   • The logic flow is easy to follow
   • The class name SearchInInfiniteSortedArray is descriptive
   • The solution properly uses the ArrayReader interface

5. Efficiency: The solution is efficient and doesn't have any unnecessary operations.

The student's solution is functionally equivalent to the reference solution. The only minor differences are:

• Language (Java vs C++)
• Class name (SearchInInfiniteSortedArray vs Solution)
• Minor stylistic differences in the exponential search loop (using high *= 2 instead of high = high * 2)

FEEDhis:

• The solution correctly implements the exponential search followed by binary search approach
• Code is clean, readable, and follows good practices
• Time and space complexity match the reference solution
• The algorithm handles edge cases properly

Areas for minor improvement:

• Could add comments explaining the two-phase approach for better documentation
• The class name could be more aligned with the problem context (though this is minor)

EEDBACK:
Your solution is excellent and correctly implements the optimal approach for this problem. Here are some observations:

Strengths:

1. Correct Algorithm: You correctly identified the two-phase approach - exponential search to find bounds, then binary search within those bounds.
2. Clean Code: The code is well-structured, readable, and follows good Java conventions.
3. Optimal Complexity: Both time (O(log n)) and space (O(1)) complexity match the reference solution.
4. Edge Case Handling: The solution properly handles cases where the target is not in the array.

Minor Suggestions for Improvement:

1. Add Comments: Consider adding brief comments explaining the two-phase approach (exponential search + binary search) to make the code more self-documenting.
2. Variable Naming: The variable names are good, but you could consider more descriptive names like bound instead of high in the first loop to clarify its purpose.
3. Class Naming: While SearchInInfiniteSortedArray is descriptive, in a typical LeetCode context, Solution is the expected class name.

Overall, this is a high-quality solution that demonstrates a strong understanding of the problem and efficient algorithm design.

VERDICT: PASS

VERDICT: PASS

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Search a 2D Matrix

It appears there has been a significant mix-up with your submission. The problem you were asked to solve is "Search a 2D Matrix," which involves searching for a target value in a 2D matrix where:

• Each row is sorted in non-decreasing order
• The first integer of each row is greater than the last integer of the previous row

You need to write a solution that:

1. Treats the 2D matrix as a single sorted 1D array of size m*n
2. Performs binary search on this virtual array
3. Converts the middle index to 2D coordinates using: row = mid/n, col = mid%n
4. Compares matrix[row][col] with the target

Please resubmit with the correct solution for the "Search a 2D Matrix" problem. The reference solution shows the expected approach clearly.

VERDICT: NEEDS_IMPROVEMENT