思路:借助栈实现,或使用递归的方法。
代码实现:
import java.util.ArrayList;
import java.util.Stack;
//定义链表结构,如果这部分代码放到类Offer05里面就会报错;如果非把ListNode放到类Offer05里面就要在class ListNode{...}前面加上static
class ListNode{
ListNode next;
int val;
}
public class Offer05 {
public ArrayList<Integer> printListFromTailToHead(ListNode listNode){
ArrayList<Integer> list = new ArrayList<>();
if(listNode == null)
return list;
Stack<ListNode> stack = new Stack<>();
while(listNode != null){
stack.push(listNode);
listNode = listNode.next;
}
while(!stack.isEmpty()){
list.add(stack.pop().val);
}
return list;
}
public static void main(String[] args) {
Offer05 of5 = new Offer05();
//测试用例
//1,功能测试(输入的链表有多个节点,输入的链表只有一个节点)
ListNode node1 = new ListNode();
ListNode node2 = new ListNode();
ListNode node3 = new ListNode();
node1.val = 1;
node2.val = 2;
node3.val = 3;
node1.next = node2;
node2.next = node3;
System.out.println(of5.printListFromTailToHead(node1));
ListNode node4 = new ListNode();
node4.val = 4;
System.out.println(of5.printListFromTailToHead(node4));
//2,特殊输入测试(输入的链表头节点指针为null)
ListNode node5 = null;
System.out.println(of5.printListFromTailToHead(node5));
}
}
输出结果: