日常学习之数据结构与算法

• 输入一个链表，按链表从尾到头的顺序返回一个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<Integer>();
        while(null != listNode){
          list.add(0,listNode.val);
          listNode = listNode.next;
        };
        return list;
    }
}

or

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

• 栈特有方法