Create linkedlist-1.java

[Praniksha123]

No description provided.

[super30admin]

Reverse Linked List (linkedlist-1.java)

Strengths:

• Clean, well-commented code with clear explanation of the approach
• Correct implementation of the iterative reversal algorithm
• Proper use of temporary variable to avoid losing reference to next node
• Optimal time and space complexity matching the reference solution

Areas for Improvement:

• The null check if(head==null) return head; is unnecessary since the while loop naturally handles this case and returns null anyway
• Consider adding a recursive solution as well since the problem mentions "Could you implement both?" in the follow-up
• For better code style, consider consistent spacing around operators (e.g., curr != null instead of curr!=null)

Overall Assessment:
The solution for the Reverse Linked List problem is correct, efficient, and well-written. It matches the reference solution in both time and space complexity.

VERDICT: PASS

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Remove Nth Node From End of List

Strengths:

1. Problem 2 shows excellent understanding of the two-pointer technique - this is actually superior to the reference solution as it achieves one-pass solution as required by the follow-up.
2. Code is well-commented with clear explanations of the approach.
3. Proper handling of edge cases (null checks, dummy node usage).
4. Good variable naming and code structure throughout.

Areas for Improvement:

1. Problem 3 could be optimized to O(1) space using Floyd's cycle detection algorithm (slow/fast pointers) instead of HashSet.
2. In Problem 2, the temp variable and subsequent null assignment is unnecessary in Java as the garbage collector will handle it - this is just a minor style observation.

Overall, the student demonstrates strong understanding of linked list operations and algorithmic thinking.

VERDICT: PASS

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Linked List Cycle II

Strengths:

1. Clear and well-documented code with step-by-step comments
2. Correct logic for cycle detection using HashSet
3. Proper handling of edge cases (null head)
4. Good variable naming conventions

Areas for Improvement:

1. Space Complexity: The problem explicitly asks for O(1) space solution in the follow-up. Consider implementing Floyd's cycle detection algorithm (slow and fast pointers) which achieves O(1) space.
2. Minor Bug: Line if(head==null) return head; should return null instead of head for correctness, though functionally they are equivalent here.
3. The student provided solutions for multiple problems but only problem 3 is relevant to the actual task.

Suggested Improvement:
To achieve O(1) space, implement the two-pointer approach:

• Phase 1: Use slow and fast pointers to detect if a cycle exists
• Phase 2: If cycle exists, reset slow to head and move both pointers one step at a time until they meet at the cycle start

VERDICT: NEEDS_IMPROVEMENT