剑指offer —— 从尾到头打印链表

/**
*    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) {
        
    }
}

 public ArrayList<Integer> printListFromTailToHead(ListNode listNode) {
        ArrayList<Integer> result = new ArrayList<>();
        if(listNode != null){
            addToList(listNode,result);
        }
        return result;
    }
    
  public void addToList(ListNode listNode,ArrayList<Integer> result){
        if(listNode.next != null){
            getNode(listNode.next,result);
        }
        //只有在当前节点中没有下个节点的时候才会执行添加方法
        result.add(listNode.val);
    }

public ArrayList<Integer> printListFromTailToHead(ListNode listNode) {
        
        ArrayList<Integer> tempList = new ArrayList<>();
        
        while(listNode != null){
            tempList.add(listNode.val);
            listNode = listNode.next;
        }
        
        ArrayList<Integer> result = new ArrayList<>(tempList.size());
        for(int i = tempList.size()-1; i >= 0; i--){
            result.add(tempList.get(i));
        }
        return result;
    }

import java.util.Stack;
import java.util.ArrayList;
public class Solution {
    
    public ArrayList<Integer> printListFromTailToHead(ListNode listNode) {
        Stack<Integer> stack = new Stack<>();
        while(listNode != null){
            stack.push(listNode.val);
            listNode = listNode.next;
        }
        
        ArrayList<Integer> result = new ArrayList<>(stack.size());
        while(!stack.isEmpty()){
            result.add(stack.pop());
        }
        return result;
    }
}