Completed PreCourse-2 exercises in Python

[allurkarsneha]

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[super30admin]

Exercise 1 (Binary Search):

• Correctness: The implementation is correct. Binary search is properly implemented with standard logic.
• Time Complexity: O(log n) - Correct.
• Space Complexity: O(1) - Correct.
• Code Quality: Clean, well-documented with comments explaining the approach. Good variable naming.
• Edge Cases: Handles the case when element is not found by returning -1.

Exercise 2 (Quick Sort - Recursive):

• Correctness: Correct implementation of Lomuto partition scheme. The algorithm properly places pivot in correct position.
• Time Complexity: O(n log n) average, O(n²) worst case - Correct.
• Space Complexity: O(log n) average, O(n) worst case - Correct.
• Code Quality: Well-structured with clear comments. The partition function is clean and follows standard conventions.
• Edge Cases: Works correctly for the test case provided.

Exercise 3 (Linked List Middle Element):

• Correctness: Correct use of slow/fast pointer technique. Properly handles the case when fast reaches the end.
• Time Complexity: O(n) for printMiddle - Correct.
• Space Complexity: O(n) for storage, O(1) for printMiddle - Correct.
• Code Quality: Clean class structure with proper separation of Node and LinkedList classes. Good use of comments.
• Edge Cases: Properly checks if head is not None before traversing.

Exercise 4 (Merge Sort):

• Correctness: Correct implementation of merge sort with proper divide-and-conquer approach. All merging logic is correct.
• Time Complexity: O(n log n) - Correct.
• Space Complexity: O(n) - Correct.
• Code Quality: Well-documented with clear step-by-step comments. The merge logic handles all cases properly.
• Edge Cases: Properly handles arrays of various sizes.

Exercise 5 (Quick Sort - Iterative):

• Correctness: Correct iterative implementation using a stack to simulate recursion. The partition logic is identical to Exercise 2.
• Time Complexity: O(n log n) average, O(n²) worst case - Correct.
• Space Complexity: O(n) for the stack - Correct.
• Code Quality: Excellent test coverage with multiple test cases including edge cases like single element and empty array. Good verification approach with expected vs actual comparison.
• Edge Cases: Well-tested with various scenarios including reverse sorted, duplicate elements, and edge cases.

Overall Assessment:
All five exercises demonstrate a solid understanding of fundamental algorithms and data structures. The student shows good programming practices including:

• Clear documentation and comments
• Proper complexity analysis
• Good variable naming conventions
• Comprehensive testing approaches (especially in Exercise 5)

Minor suggestions for improvement:

• Could add type hints for better code documentation
• Could include more edge case testing in Exercises 1-4
• Exercise 5 could benefit from checking for empty array before accessing indices