Reverse a singly linked list iteratively and recursively

How to frame this at Cognizant: Connect your answer to measurable impact, clarity of thought, and trade-offs the team cares about. Below is a strong baseline response you can adapt with your own project examples.

Iterative approach uses three pointers: prev, curr, next. Rewire curr.next to prev, advance all pointers until curr is null; return prev as new head.

function reverseList(head) {
  let prev = null, curr = head;
  while (curr) {
    const next = curr.next;
    curr.next = prev;
    prev = curr;
    curr = next;
  }
  return prev;
}

Recursive: reverse rest of list, then set head.next.next = head and head.next = null. Base case: empty or single node.

Time O(n), space O(1) iterative or O(n) recursion stack. Mention reversing in groups, palindrome check, and cycle detection (Floyd) as follow-ups.