s30 design-2 completed - hashmap and queue from stacks

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Implement Queue using Stacks (queue_from_stack.py)

Strengths:

• Clean, well-organized code that closely follows the optimal approach
• Correct implementation of the two-stack queue pattern
• Good variable naming conventions
• Proper handling of edge cases

Areas for Improvement:

• The time complexity analysis in comments is incomplete. While operations appear O(1), you should note that pop() and peek() have O(n) worst-case complexity when the output stack is empty and transfer is needed. The amortized complexity is O(1), but individual operations can be expensive.
• Consider adding a brief comment explaining why the transfer works (reversing stack order to simulate queue FIFO)

VERDICT: PASS

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Design HashMap (.idea/Design-2.iml)

Unfortunately, there is no code to evaluate. The submitted file is an IDE configuration file, not a solution to the HashMap problem. To improve, the student should:

1. Submit actual Java/Python code implementing the MyHashMap class
2. Follow the problem requirements: implement put(), get(), and remove() methods
3. Use appropriate data structures (array of linked lists or similar for chaining)
4. Ensure the implementation handles key updates and returns -1 for non-existent keys

The reference solution demonstrates a proper approach using:

• An array of buckets (Node objects)
• Separate chaining with linked lists for collision handling
• Helper methods for hashing and finding previous nodes

FEEDBACK:
No code was submitted. The student needs to provide an actual implementation of the MyHashMap class with put(), get(), and remove() methods. Please review the problem description and reference solution, then submit working code.

VERDICT: NEEDS_IMPROVEMENT