隊列演示

隊列

隊列是先進先出，與堆棧不一樣

數組實現

數組實現主要採用雙指針方式

package com.example.data;

/**
 * *@ClassName QueueList
 * *@Author yyc
 * *@Date 2020/6/15 15:15
 **/
public class QueueList {

    //頭指針
    private int Head;
    //尾指針
    private int Tail;

    private int[] result;

    private int len;

    //初始化隊列數組
    public QueueList(int length)
    {
        this.len=length;
        this.result=new int[length];
        this.Head=0;
        this.Tail=0;
    }

    //往隊列中壓入數據
    public void Enqueue(int value)
    {
        if(Tail<len)
        {
            result[Tail++] = value;
        }
    }

    public int Dequeue() throws Exception {
        if(Head<=Tail)
        {
            return result[Head++];
        }
        else
           throw  new Exception("超出範圍");
    }


}

鏈表隊列

package com.example.data;

/**
 * *@ClassName QueueLinked
 * *@Author yyc
 * *@Date 2020/6/15 16:17
 * 鏈表隊列
 **/
public class QueueLinked {

    //頭鏈表
    public Node head;
    //尾鏈表
    public Node Tail;

    //鏈表長度
    private  int N;

    public QueueLinked(){
        head=new Node(null,null);
        Tail=null;
        N=0;
    }

    /**
     * 判斷是否爲空鏈表
     * @return
     */
    public boolean isEmpty(){
        return N==0;
    }


    public void push(Integer value)
    {
       if(Tail==null)
       {
           Tail=new Node(value,null);
           head.next=Tail;
       }
       else
       {
            Node oldLast=Tail;
            Tail=new Node(value,null);
            oldLast.next=Tail;
       }
       N++;
    }

    public Integer pop(){
        if(isEmpty()) {
            return null;
        }

        Node oldFirst=head.next;

        head.next=oldFirst.next;
        N--;
        if(isEmpty())
        {
            Tail=null;
        }

        return (Integer) oldFirst.item;
    }
}