Complete PreCourse-1

[pcparagc]

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[super30admin]

Exercise_1.py (List-based Stack):

• Correctness: The implementation is correct with proper handling of edge cases (isEmpty check before pop/peek).
• Time Complexity: O(1) for all operations is accurate.
• Space Complexity: O(n) is correct.
• Code Quality: Good implementation, but lacks docstrings and the comments about Leetcode are incomplete. The indentation of the complexity comments is inconsistent.

Exercise_2.py (Linked List-based Stack):

• Correctness: Implementation is correct with proper head insertion for push and head removal for pop.
• Time Complexity: O(1) for both push and pop is correct.
• Space Complexity: O(n) is correct.
• Code Quality: Well-structured with a separate Node class. The interactive driver code is helpful for testing. Could benefit from additional methods like peek(), isEmpty(), and size() for a complete stack implementation.

Exercise_3.py (Singly Linked List):

• Correctness: Implementation is correct. The append, find, and remove methods work as expected.
• Time Complexity: O(n) for all three methods is accurate.
• Space Complexity: The comment claims O(1) but this is misleading - space complexity for the data structure itself is O(n) for storing n elements. O(1) auxilary space is more accurate.
• Code Quality: Good use of docstrings explaining time complexity. The code is clean and readable. Consider adding a show() or traverse() method for debugging purposes.

General Observations:

• All three files show good understanding of data structures.
• The student consistently includes time/space complexity comments (though some are incomplete/misleading).
• Code structure is clean with proper use of classes and methods.
• Edge case handling is present but could be more comprehensive (e.g., handling None values in linked list operations).