- 输入一个链表，按链表值从尾到头的顺序返回一个ArrayList。完成如下代码：
/**
* 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) {
}
}
- 思路：看到从尾到头想到栈，遍历链表，压入栈，遍历栈，写入ArrayList
- 代码：
public class Solution {
public ArrayList<Integer> printListFromTailToHead(ListNode listNode) {
ArrayList<Integer> list = new ArrayList<Integer>();
if (listNode == null) {
return list;
}
Stack<ListNode> stack = new Stack<ListNode>();
while (listNode != null) {
stack.push(listNode);
listNode = listNode.next;
}
while (!stack.empty()&&stack.peek()!=null){
list.add(stack.pop().val);
}
return list;
}
}
