Added solutions

[sandeepkumarks]

Completed Linked-List-1

[super30admin]

Reverse Linked List (ReverseLinkedList.java)

Strengths:

• Clean and concise implementation that matches the reference solution exactly
• Good variable naming (prev, current, next) that clearly describes their roles
• Correctly handles the base case of an empty list
• Proper use of temporary variable to preserve the next node before reversing

Areas for Improvement:

• The code lacks the standard class structure with proper imports and the ListNode class definition, which would be needed for compilation
• The comment block is helpful but could be more detailed, explaining the algorithm step-by-step
• Consider adding a brief explanation of why the algorithm works (when the loop ends, prev points to the last original node which is now the new head)

Comparison to Reference:

• Time Complexity: O(n) - Same as reference ✓
• Space Complexity: O(1) - Same as reference ✓
• Correctness: Correct ✓

The solution is functionally equivalent to the reference and demonstrates a solid understanding of the linked list reversal problem.

VERDICT: PASS

---

Remove Nth Node From End of List (RemoveNthNode.java)

Strengths:

• Good use of the dummy head pattern, which is a best practice for linked list problems
• Clear comments explaining the algorithm approach
• Correctly handles edge cases like removing the head node
• Time and space complexity match the optimal solution

Areas for Improvement:

1. The index variable is redundant - you can simply count how many times you move current forward
2. The final if(index == 1) block is unnecessary. Since dummyHead.next points to the original head, and you're modifying dummyHead.next directly via current.next = current.next.next, the dummy head already "knows" about the new head. You can simply return dummyHead.next instead of the convoluted head reassignment.
3. Consider combining the traversal logic - you can directly traverse targetIndex - 1 steps without a separate index counter

Suggested Refactor:

current = dummyHead;
for(int i = 0; i < targetIndex - 1; i++) {
    current = current.next;
}
current.next = current.next.next;
return dummyHead.next;

This is cleaner and more direct.

VERDICT: PASS

---

Linked List Cycle II (LinkedListCycleII.java)

Strengths:

1. Correctly implements the Floyd's cycle detection algorithm
2. Clean, readable code with good variable naming
3. Appropriate comments explaining the approach
4. Handles edge cases properly (empty list, no cycle)
5. Achieves optimal O(n) time and O(1) space complexity

Areas for Improvement:

1. The isCycleExists boolean is unnecessary - you can simply check if(slow == fast) after the loop to determine if a cycle was found
2. Consider combining variable declaration: ListNode slow = head, fast = head;
3. The comment header format is good but could include more details about the algorithm's mathematical basis

Overall, this is a solid implementation that demonstrates good understanding of the problem and algorithm.

VERDICT: PASS