(FB) 链表的递归与倒序打印

(FB) 在不修改链表结构和数据的情况下，倒序输出链表

他妈的，写完代码之后发现我特意建一个页面总结这题的目的是什么。。

• 递归

• 迭代

    private static void reversePrintList_recursive(ListNode head){
        if(head.next == null){
            System.out.print(head.val + ",");
            return;
        }
        reversePrintList_recursive(head.next);
        System.out.print(head.val + ",");
    }

    private static void reversePrintList_iterative(ListNode head){
        int size = 0;
        ListNode cur = head;
        while(cur != null){
            size++;
            cur = cur.next;
        }

        for(; size > 0; size --){
            ListNode ptr = head;
            for(int i = 0; i < size - 1; i++) ptr = ptr.next;
            System.out.print(ptr.val + ",");
        }
    }

    public static void main(String[] args) {
        // 5 -> 4 -> 3 -> 2 -> 1 -> 0 -> NULL

        ListNode node5 = new ListNode(5);
        ListNode node4 = new ListNode(4);
        ListNode node3 = new ListNode(3);
        ListNode node2 = new ListNode(2);
        ListNode node1 = new ListNode(1);
        ListNode node0 = new ListNode(0);

        node5.next = node4;
        node4.next = node3;
        node3.next = node2;
        node2.next = node1;
        node1.next = node0;

        reversePrintList_recursive(node5);
        reversePrintList_iterative(node5);
    }