S30/feature

[piyushd-techie93]

added pr comments

[super30admin]

The student has demonstrated a good understanding of implementing stacks using both arrays and linked lists, as well as basic linked list operations. Here are some specific observations:

1. Correctness:

• Exercise_1 (Array Stack): The implementation is correct with proper checks for overflow/underflow. The peek() method could be improved to print a message when stack is empty (like pop() does).
• Exercise_2 (Linked List Stack): Correct implementation with proper handling of edge cases. The isEmpty() method could be simplified to just return root == null.
• Exercise_3 (Linked List): There's a compilation error as 'head' is not accessible in static methods. The head should be accessed through the list parameter (list.head). The insert method needs to handle this properly.

2. Time Complexity:

• The student has correctly identified the time complexities for all operations in all exercises.

3. Space Complexity:

• Space complexities are correctly identified for all operations.

4. Code Quality:

• Generally good, but could be improved with:
  • Consistent error messages (some say "stack empty", others "Stack Underflow")
  • Better method documentation/comments
  • In Exercise_3, the LinkedList class should properly encapsulate its head field
  • Remove unused imports (com.practise.s30.LinkedList in Exercise_3)

5. Efficiency:

• The implementations are efficient for the given problems. No major optimizations needed beyond the fixes mentioned above.

Main issues to address:

• Fix the compilation error in Exercise_3 by properly accessing the head through the list parameter
• Improve consistency in error messages
• Better encapsulation of class fields
• Remove unused imports