package com.zoujc;

/**
 * 用連結串列實現棧
 */
class MyLinkStack {
    private Link first;
    public MyLinkStack(){
        first = null;
    }
    //判空
    public boolean isEmpty(){
        return first == null;
    }
    //從頭插入
    public void insertFirst(int dd){
        Link link = new Link(dd);
        link.
 
next = first;
        first = link;
    }
    //刪除
    public int deleteFirst(){
        Link tmp = first;
        first = first.next;
        return tmp.dData;
    }
    //顯示
    public void display(){
        Link current = first;
        while (current != null){
            current.display();
            current =
 
 current.next;
        }
        System.out.println("");
    }
}
class Link{
    public int dData;
    public Link next;
    public Link(int dd){
        dData = dd;
    }
    public void display(){
        System.out.print(dData + " ");
    }
}
class LinkStack{
    public MyLinkStack myLinkStack;
    public
 
 LinkStack(){
        myLinkStack = new MyLinkStack();
    }
    //進棧
    public void push(int data){
        myLinkStack.insertFirst(data);
    }
    //出棧
    public int pop(){
        return myLinkStack.deleteFirst();
    }
    //判空
    public boolean isEmpty(){
        return myLinkStack.isEmpty();
    }
    //顯示
    public void display(){
        System.out.print("Stack:");
        myLinkStack.display();
    }
    public static void main(String[] args){
        LinkStack linkStack = new LinkStack();
        linkStack.push(20);
        linkStack.push(30);
        linkStack.push(40);
        linkStack.display();
        linkStack.pop();
        linkStack.pop();
        linkStack.display();
    }
}