# Complete Pre Course - 1

[mgpadshala]

No description provided.

[super30admin]

The student has provided solutions for three different exercises involving stack and linked list implementations. Here's a detailed evaluation:

1. Exercise_1.py (Array-based Stack):

• Correctness: The implementation correctly follows stack operations (LIFO) using a list. Edge cases like empty stack are handled well.
• Time Complexity: Accurately documented for all operations. The show() method's O(N) complexity is correctly justified.
• Space Complexity: Correctly identified as O(N).
• Code Quality: Well-structured and readable. Good use of comments explaining each method.
• Improvement: Could add input validation for push() to ensure only valid data types are pushed.

2. Exercise_2.py (Linked List-based Stack):

• Correctness: Properly implements stack using linked list with correct push/pop operations at head.
• Time Complexity: Correctly documented as O(1) for push/pop.
• Space Complexity: Correctly identified as O(N).
• Code Quality: Clean implementation. The interactive part could be separated from the class for better modularity.
• Improvement: Could add a peek() method for completeness. The size tracking is good but not strictly necessary.

3. Exercise_3.py (Singly Linked List):

• Correctness: Basic operations (append, find, remove) are correctly implemented.
• Time Complexity: Correct for append (O(n)), find (O(n)), and remove (O(n)).
• Space Complexity: Not documented but is O(n).
• Code Quality: Good structure. The remove() method could be simplified by handling head case separately.
• Improvement: Could add a str method for better debugging. The dummy node in remove() is clever but might confuse beginners.

General Strengths:

• Good documentation of time/space complexity
• Proper handling of edge cases
• Clean, readable code structure
• Appropriate use of data structures

Areas for Improvement:

• More complete method sets (e.g., peek() in Exercise_2)
• Better separation of test code from implementations
• More consistent error handling (some methods print, others return None)
• Could add more input validation