PreCourse1 all 3 exercise solutions in java

[GOUTHAM9955]

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[super30admin]

The student's solutions demonstrate a good understanding of basic data structures (stack and linked list) and their operations. Here's a detailed evaluation:

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

• Correctness: The implementation correctly handles stack operations (push, pop, peek) with proper overflow/underflow checks.
• Time/Space Complexity: Correctly identified as O(1) for all operations.
• Code Quality: Well-structured with clear comments. The isEmpty() method could be simplified to just return top == -1;.
• Edge Cases: Properly handles empty stack and full stack scenarios.

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

• Correctness: Correct implementation of stack operations using linked list nodes.
• Time/Space Complexity: Correctly identified as O(1) for all operations.
• Code Quality: Good structure, though the "Pushed to stack" message in push() might be unnecessary.
• Edge Cases: Properly handles empty stack scenario.

3. Exercise_3.java (Linked List):

• Correctness: Correct implementation of linked list insertion and printing.
• Time Complexity: Correctly identified insertion as O(n) (though the comment about tail node optimization is good).
• Code Quality: Well-structured, but the insert method could be more efficient by maintaining a tail pointer.
• Edge Cases: Properly handles empty list scenario.

General Improvements:

1. Consider adding more test cases in main() methods to verify edge cases.
2. For Exercise_3, maintaining a tail pointer would indeed improve insertion time to O(1).
3. Some redundant comments could be removed (like "Write your code here").
4. Consider adding documentation comments for methods.