reversed-linked-list_recursive.js

class ListNode {
  constructor(value) {
    this.value = value;
    this.next = null;
  }
}

function reverseLinkedList(head, prev = null) {
  if (head === null) {
    return prev;
  }
  const nextNode = head.next;
  head.next = prev;
  return reverseLinkedList(nextNode, head);
}

// Example usage:
const createLinkedListFromArray = (arr) => {
  const dummyHead = new ListNode(null);
  let current = dummyHead;
  for (let value of arr) {
    current.next = new ListNode(value);
    current = current.next;
  }
  return dummyHead.next;
};

const printLinkedList = (head) => {
  let current = head;
  let result = [];
  while (current) {
    result.push(current.value);
    current = current.next;
  }
  console.log(result.join(' -> '));
};

const array = [1, 2, 3, 4, 5];
const head = createLinkedListFromArray(array);
printLinkedList(head); // Output: 1 -> 2 -> 3 -> 4 -> 5

const reversedHead = reverseLinkedList(head);
printLinkedList(reversedHead); // Output: 5 -> 4 -> 3 -> 2 -> 1