从尾到头打印链表

public class Solution {// 递归实现
    ArrayList<Integer> result = new ArrayList<>();
    public ArrayList<Integer> printListFromTailToHead(ListNode listNode){
        if(listNode != null){
            this.printListFromTailToHead(listNode.next);
            result.add(listNode.val);
        }
        return result;
    }
    
    // 借用stack
    public ArrayList<Integer> printListFromTailToHead3(ListNode listNode) {
        Stack<Integer> stack = new Stack<>();
        ArrayList<Integer> list = new ArrayList<>();
        while(listNode!=null){
            stack.push(listNode.val);
            listNode = listNode.next;
        }
        while(!stack.isEmpty()){
            list.add(stack.pop());
        }
        return list;
    }
}