反转链表

Question

给你单链表的头节点 head ，请你反转链表，并返回反转后的链表。

输入：head = [1,2,3,4,5]
输出：[5,4,3,2,1]

function reverseLinkedList(head) {
    let prev = null
    let cur = head
    while (cur) {
        const next = cur.next
        cur.next = prev
        prev = cur
        cur = next
    }

    return prev
}