The student has submitted solutions for three exercises implementing stack and linked list data structures. Here's my evaluation:

Exercise_1.cs (Array-based Stack):

• Correctness: The implementation correctly handles stack operations (push, pop, peek) with proper underflow checks. The resize functionality for dynamic array expansion is a good addition.
• Time Complexity: Correctly identified as O(1) for all operations except push which is O(n) when resizing.
• Space Complexity: Correctly identified as O(n).
• Code Quality: Well-structured with clear method separation. Could benefit from more comments explaining the resize logic.
• Improvement: Consider adding a capacity check in the constructor and making MAX a property rather than a constant.

Exercise_2.cs (Linked List-based Stack):

• Correctness: Properly implements stack operations with linked list nodes. Handles underflow cases correctly.
• Time Complexity: Correctly identified as O(1) for all operations.
• Space Complexity: Correctly identified as O(n).
• Code Quality: Good use of inner class for StackNode. Clear and concise methods.
• Improvement: Could add null checks in peek() similar to pop() for consistency.

Exercise_3.cs (Linked List Implementation):

• Correctness: Basic linked list operations (insert and print) are correctly implemented.
• Time Complexity: Insert is O(n) as it traverses to the end, which is correctly identified.
• Space Complexity: Correctly identified as O(n).
• Code Quality: Good structure but has a Java-like main method (should be Main in C#). The printList method could be made non-static for better OOP.
• Improvement: Consider adding methods for other operations like delete and search.

General Feedback:

1. The solutions demonstrate good understanding of data structures.
2. Consistent error handling for stack underflow cases.
3. Good separation of concerns in each implementation.
4. Could benefit from more comprehensive test cases in the driver code.
5. Some minor C# conventions could be improved (like using properties instead of public fields).