队列/两个队列实现一个栈

顺序队列的实现

/**
 * @auther: 巨未
 * @DATE: 2019/1/5  20:17
 * @Description: 顺序队列
 */
class Cqueue{
    private int front;
    private int rear;
    private int[] elem;
    private int usedSize; //有序数据个数
    private int allSize = 0; //总共的大小

    public Cqueue(){
        this(10);
    }
    public Cqueue(int size){
        this.elem = new int[size];
        this.front = 0;
        this.rear = 0;
        this.usedSize = 0;
    }
    /*是否为满*/
    public boolean isFull(){
        if((rear+1)%allSize == front) {    //7+1   %8   =0
            return true;
        }
        return false;
    }
    /*入队*/
    public void push(int val) {
        if(isFull()) {
            return;
        }
        this.elem[this.rear] = val;   //rear不能++
        this.rear = (this.rear+1)%allSize; // 1+1  %8 == 1
        this.usedSize++;
    }
    /*是否为空*/
    public  boolean isEmpty(){
        if(this.rear == this.front){
           return true;
        }
        return false;
    }
    /*出队*/
    public int pop(){
        if(isEmpty()){
            throw new UnsupportedOperationException("队列为空");
        }
       int num = this.elem[this.front];
        this.front = (this.front+1) % allSize;
        this.usedSize --;
        return num;
    }
    /*得到队头元素*/
    public int getTop(){
        if(isEmpty()){
            throw new UnsupportedOperationException("队列为空");
        }
        return this.elem[this.front];
    }
    /*打印*/
    public void show(){
        for (int i = this.front; i != this.rear; i = (i+1)%allSize) {
            System.out.print(this.elem[i]+ " ");
        }
        System.out.println();
    }
    public int getUsedSize(){
        return this.usedSize;
    }


}

两个队列实现一个栈

public class CqueueDemo {
    /*两个队列实现一个栈：入栈*/
    public static void pushStack(Cqueue qu1,Cqueue qu2,int val){
        Cqueue queue ; //要入队的队列
        if(!qu1.isEmpty()){
            queue = qu1;
        }else{
            queue = qu2;
        }
        queue.push(val);
    }
    /*两个队列实现一个栈：出栈*/
    public static int popStcak(Cqueue qu1,Cqueue qu2){
        Cqueue pQueue1; //要出队的那个队列
        Cqueue pQueue2; //从pQueue1出队的数据放到pQueue2
        if(!qu1.isEmpty()){
            pQueue1 = qu1;
            pQueue2 = qu2;
        }else {
            pQueue1 = qu2;
            pQueue2 = qu1;
        }
        int tmp = 0;
        if(pQueue1.isEmpty()){
            System.out.println("is Empty");
        }else{  //将pQueue的数据出的只剩下一个，放入pQueue2

            while(pQueue1.getUsedSize()>1) {
               tmp = pQueue1.pop();
                pQueue2.push(tmp);
            }
           return pQueue1.pop();
            }
            return -1;
        }

    public static void main(String[] args) {
      Cqueue cqueue = new Cqueue();
      cqueue.push(10);
        cqueue.push(20);
        cqueue.push(31);
        cqueue.push(40);
        cqueue.show();
        System.out.println(cqueue.pop());
        cqueue.show();
        cqueue.getTop();
    }
}