1. 程式人生 > >3.從尾到頭列印連結串列

3.從尾到頭列印連結串列

輸入一個連結串列,按連結串列值從尾到頭的順序返回一個ArrayList。

 

 

/**
*    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<>(); if(listNode==null)return list; if(listNode.next==null){ list.add(listNode.val); return list; } while (listNode.next!=null){ list.add(listNode.val); listNode=listNode.next; } list.add(listNode.val); ArrayList
<Integer> list1=new ArrayList<>(); for(int i=list.size()-1;i>=0;i--){ list1.add(list.get(i)); } return list1; } }

import java.util.ArrayList;
import java.util.List;
import java.util.Stack;

public class Solution {
    public class ListNode {
        
int val; ListNode next = null; ListNode(int val) { this.val = val; } } public static ArrayList<Integer> printListFromTailToHead(ListNode listNode) { Stack<Integer> stack = new Stack<>(); while (listNode != null) { stack.push(listNode.val); listNode = listNode.next; } ArrayList<Integer> list = new ArrayList<>(); while (!stack.isEmpty()) { list.add(stack.pop()); } return list; } }