(Js) Leetcode 206. Reverse linked list

topic:

Reverse a singly linked list.

Example:

输入: 1->2->3->4->5->NULL
输出: 5->4->3->2->1->NULL

Ideas:

Use recursive implementation

Code:

/**
 * Definition for singly-linked list.
 * function ListNode(val, next) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.next = (next===undefined ? null : next)
 * }
 */
/**
 * @param {ListNode} head
 * @return {ListNode}
 */
var reverseList = function (head) {
   if (head == null || head.next == null) {
        return head;
    }
    const newHead = reverseList(head.next);
    head.next.next = head;
    head.next = null;
    return newHead;
};

operation result: