链表中倒数第k个节点

var getKthFromEnd = function(head, k) {
    let fast = head, slow = head;
    while (fast && k > 0) {
        [fast, k] = [fast.next, k - 1];
    }
    while (fast) {
        [fast, slow] = [fast.next, slow.next];
    }
    return slow;
};

https://leetcode-cn.com/problems/lian-biao-zhong-dao-shu-di-kge-jie-dian-lcof/