day3

输入一个链表的头节点，从尾到头反过来返回每个节点的值（用数组返回）。

 

示例 1：

输入：head = [1,3,2]
输出：[2,3,1]

class ListNode {
    val: number;
    next: ListNode | null;
    constructor(val?: number, next?: ListNode | null) {
        this.val = val === undefined ? 0 : val;
        this.next = next === undefined ? null : next;
    }
}
function reversePrint(head: ListNode | null): number[] {
    return head == null ? [] : reversePrint(head.next).concat(head.val);
}
const list: number[] = [ 2, 3, 1 ];
//reversePrint(3).concat(2);
//reversePrint(reversePrint(1).concat(3);).concat(2);
//(reversePrint(reversePrint(reversePrint(null).concat(1)).concat(3)).concat(2);
//(([].concat(1)).concat(3)).concat(2)
//([1].concat(3)).concat(2)
//[1,3].concat(2)
//[1,3,2]