Completed PreCourse-1

[gurneetk186]

No description provided.

[super30admin]

The student has submitted multiple implementations of stack data structures in different languages (Java and C++). Here's my evaluation of each:

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

• Correctness: The implementation correctly handles stack operations (push, pop, peek, isEmpty) with proper overflow/underflow checks.
• Time Complexity: Correctly identified as O(1) for all operations.
• Space Complexity: Correctly identified as O(MAX) where MAX is the fixed array size.
• Code Quality: Well-structured with clear comments. Could benefit from making MAX a final constant.
• Edge Cases: Handles underflow/overflow cases well.

2. Exercise_2.cpp (Linked List Stack):

• Correctness: Implementation is mostly correct but uses INT_MIN as error return which isn't ideal (could use exceptions or optional).
• Time Complexity: Correctly identified as O(1) for all operations.
• Space Complexity: Correctly identified as O(n) where n is number of elements.
• Code Quality: Good structure but could use more comments. The use of double pointers (**) might be confusing for beginners.
• Edge Cases: Handles empty stack cases but INT_MIN might not be the best error indicator.

3. Exercise_3.java (Linked List):

• Correctness: Implements a basic linked list rather than a stack, which appears to be a different problem.
• Time Complexity: Insert is O(n) which is correct for linked list append.
• Space Complexity: Correctly identified as O(n).
• Code Quality: Well-structured but seems to be solving a different problem than stack implementation.

4. StackAsLinkedList.java:

• Correctness: Correct stack implementation using linked list.
• Time Complexity: Correctly identified as O(1) for all operations.
• Space Complexity: Correctly identified as O(n).
• Code Quality: Good structure with clear methods. Could improve comments on pointer manipulation.
• Edge Cases: Handles empty stack cases well.

General Improvements:

1. Consistent error handling across implementations would be better.
2. Some implementations mix problem domains (like Exercise_3 implementing a list rather than stack).
3. Could benefit from more detailed comments explaining pointer manipulations.
4. Consider using exceptions or Optionals instead of special return values for error cases.