Complete LinkedList-1

[dhruvil15]

No description provided.

[super30admin]

Reverse a LinkedList (Problem49.java)

Strengths:

• The solution is correct and efficient, with optimal time and space complexity.
• The code is clean and easy to read, with meaningful variable names (prev, curr, temp).
• The student has included comments about time and space complexity, which is good practice.

Areas for Improvement:

• While the code is correct, it would be beneficial to handle edge cases explicitly, such as an empty list (head is null) or a list with only one node. However, the current code handles these cases correctly because the while loop condition checks for curr != null, and if head is null, the loop doesn't execute, returning prev which is null.
• The student might consider adding a brief comment explaining the approach, especially since the problem asks for both iterative and recursive solutions. However, this is not mandatory.

Overall, the solution is excellent and meets all requirements.

VERDICT: PASS

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Remove nth node (Problem50.java)

Your solution is on the right track and uses an efficient one-pass approach. Here are some points to consider:

1. The initial loop condition count <= n actually moves the fast pointer n+1 times. This is correct because you want to create a gap of n+1 between slow and fast. However, it might be clearer to write:

   for (int i = 0; i < n; i++) {
       fast = fast.next;
   }

   But note: you want fast to be n steps ahead of slow? Actually, with the dummy node, you want fast to be n+1 nodes ahead of slow. So the initial loop should move fast n+1 times. So your current loop is correct. However, the variable count is initialized to 0 and the loop runs while count <= n, which is n+1 times. This is correct. But to make it more readable, you could use a for-loop that explicitly runs n+1 times.

2. The line temp.next = null; is not necessary for the problem. It is good practice to set the next pointer of the removed node to null to help with garbage collection, but it is not required by the problem. So it's acceptable.

3. Your solution handles the edge case of removing the head node correctly by using the dummy node. This is a good practice.

4. The time and space complexity comments are correct.

5. One minor improvement: you can check if the list is empty? But the constraints say at least one node.

Overall, the solution is correct and efficient. However, there is a potential issue: what if n is 0? But constraints say n>=1, so it's safe.

VERDICT: PASS

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Cycle in linked list (Problem51.java)

Strengths:

• The solution correctly implements Floyd's cycle detection algorithm.
• It handles edge cases (like null head) appropriately.
• The code is clean and easy to read.
• Time and space complexity are optimal.

Areas for improvement:

1. The variable name flag could be more descriptive. Consider renaming it to hasCycle or something similar to improve clarity.
2. The condition in the while loop checks fast.next != null && fast.next.next != null, which is correct. However, it's important to note that this condition prevents null pointer exceptions by ensuring that fast and fast.next are not null before accessing fast.next.next.
3. The solution is written in Java, but the problem statement and reference solution are in C++. While the algorithm is language-agnostic, it's important to ensure that the solution adheres to the language-specific best practices. In Java, this code is acceptable.

Overall, the solution is excellent and meets all requirements.

VERDICT: PASS