从尾到头打印链表

leetcod返回是数组

class Solution {

    public int[] reversePrint(ListNode head) {
        if(head == null)
            return new int[]{};
        ArrayList<Integer> list = new ArrayList<>();
        while(head != null){
            list.add(head.val);
            head = head.next;
        }

        int[] nums = new int[list.size()];
        int index = 0;
        for(int i = list.size()-1; i >= 0; i--){
            nums[index++] = list.get(i);
        }
        return nums;

    }
}

牛客 直接使用递归

public class Solution {
    ArrayList<Integer> list = new ArrayList<>();
    public ArrayList<Integer> printListFromTailToHead(ListNode listNode) {
        if(listNode != null){
            printListFromTailToHead(listNode.next);
            list.add(listNode.val);
        }
        return list;
    }
}

不使用递归

/**
*    public class ListNode {
*        int val;
*        ListNode next = null;
*
*        ListNode(int val) {
*            this.val = val;
*        }
*    }
*
*/
import java.util.ArrayList;
public class Solution {
    public ArrayList<Integer> printListFromTailToHead(ListNode listNode) {
        ArrayList<Integer> list = new ArrayList<>();
        ListNode tmp = listNode;
        while(tmp!=null){
            list.add(0,tmp.val);
            tmp = tmp.next;
        }
        return list;
    }
}