栈/两个栈实现一个队列

Java实现

/*
*
 * @auther: 巨未
 * @DATE: 2019/1/5 0005 18:29
 * @Description:  顺序栈

*/

class MyStackK {
    private int[] elem;
    private int top;

    public MyStackK() {
        this(10);
    }

    public MyStackK(int size) {
        this.elem = new int[size];
        this.top = 0;
    }

//入栈

    public void push(int val) {
        if (isFull()) {
            return;
        }
        this.elem[this.top++] = val;  //放一个值，top+1
    }

//出栈

    public void pop() {
        if (isEmpty()) {
            return;
        }
        this.top--;
    }

//判满

    public boolean isFull() {   //top是否等于数组elem的长度
        if (this.top == this.elem.length) {
            return true;
        }
        return false;
    }

//判空

    public boolean isEmpty() {
        if (this.top == 0) {
            return true;
        }
        return false;
    }

//得到栈顶元素

    public int getTop() {
        if (isEmpty()) {
            throw new UnsupportedOperationException("栈为空！");
        }
         return this.elem[this.top-1];
    }

//得到栈顶元素并且删除

    public int getTop1() {
        if (isEmpty()) {
            throw new UnsupportedOperationException("栈为空！");
        }
      int data = this.elem[this.top-1];
        return data;
}
//打印栈内元素

    public void show(){
        for(int i = 0;i < this.top;i++){
            System.out.print(this.elem[i] +" ");
        }
    }

}

public class CStackDemo {
/*
*
     * 两个栈实现一个队列： 入队
     * @param s1
     * @param val

*/

    public static void pushQueue(MyStackK s1, int val) {
        //先入栈：
         s1.push(val);
    }

/**
     *两个栈实现一个队列： 出队
     * @param s1
     * @param s2
     * @return
     */

    public static int popQueue(MyStackK s1, MyStackK s2) {
        //把所有数据放到s2
        if (s2.isEmpty()) {
            int tmp = 0;
            while (!s1.isEmpty()) {
                tmp = s1.getTop();
                s2.push(tmp);
            }
        }
        //将s2栈顶元素出栈
        int tmp2 = 0;
        if (!s2.isEmpty()) {
            tmp2 = s2.getTop();
        }else {
            System.out.println("队列为空！");
        }
        return tmp2;

    }


    public static void main(String[] args) {
      MyStackK myStackK = new MyStackK();
      myStackK.push(1);
      myStackK.push(2);
      myStackK.push(4);
      myStackK.push(9);
      myStackK.push(3);
      myStackK.pop();
        System.out.println(myStackK.getTop());
        myStackK.show();

    }
}