Reverse Linked List
Difficulty: EasyTopic: Linked ListRecursionLeetcode:206.Reverse Linked ListGiven the head of a singly linked list, reverse the list, and return the reversed list.
Example 1:
Input: head = [1,2,3,4,5]
Output: [5,4,3,2,1]
Example 2:
Input: head = [1,2]
Output: [2,1]
Example 3:
Input: head = []
Output: []
Constraints:
- The number of nodes in the list is the range
[0, 5000]. -5000 <= Node.val <= 5000
Follow up: A linked list can be reversed either iteratively or recursively. Could you implement both?
Solution
write solution in here
/**
* @param {ListNode} head
* @return {ListNode}
*/
var reverseList = function (head) {
if (head == null || head.next == null) return head;
const last = reverseList(head.next);
head.next.next = head;
head.next = null;
return last;
};