JavaScript, ES6 spread 语法

/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */
/**
 * @param {ListNode} head
 * @return {Number[]}
 */
var printListReversingly = function(head) {
  return head ? [...printListReversingly(head.next), head.val] : [];
}