栈与队列数组版【Java算法（三）】

目录

1.栈

2.队列

3.测试

---

项目结构：

1.栈

Stack.java

/*
    栈：用数组实现
 */

public class Stack {

    private int[] array;
    private int top;//栈顶

    public Stack(){
        array = new int[10];
    }

    public Stack(int capacity){//栈的深度
        array = new int[capacity];
    }

    //获取栈的深度
    public int getStackLength(){
        return array.length;
    }

    /**
     * 压入栈中
     * @param element 放入的元素
     */
    public void push(int element){

        //判断是否栈满
        if(top >= array.length){
            //对栈进行扩容
            expandCapacity(top);
        }

        array[top] = element;
        top++;//栈顶加1
    }

    //弹出栈中的数据
    public int pop(){
        return array[--top];
    }

    public void expandCapacity(int top){

        int[] newArray = new int[array.length * 2];

        if(newArray.length > 100){
            throw new IllegalArgumentException("不准栈的深度超过100");
        }

        if(top > 0){
            System.arraycopy(array,0,newArray,0,top);
        }

        array = newArray;
    }

    @Override
    public String toString() {
        String str = "[";
        //只遍历数组当中的元素个数
        for(int i = 0;i < top;i++){
            str += array[i];
            //当不是最后1个元素,需要加逗号
            if(i != top - 1){
                str += ",";
            }
        }
        //最后加一个"]"结尾
        str += "]";
        return str;
    }
}

2.队列

Queue.java

/*
    队列：用数组实现
 */

import java.util.NoSuchElementException;

public class Queue {

    private int font;//队头
    private int rear;//队尾
    private int[] array;

    public Queue(){
        array = new int[10];
    }

    public Queue(int capacity){
        array = new int[capacity];
    }

    //获取队列长度
    public int getQueueLength(){
        return array.length;
    }

    //入队
    public void enQueue(int element){

        //判断队列是否队满
        if((rear + 1) % array.length == font){
            expandCapacity();
        }

        array[rear] = element;//在队尾加上数据
        rear = (rear + 1)%array.length;//添加完数据,队尾往后移
    }

    //出队
    public int outQueue(){

        //判断队列是否为空
        if(font == rear){
            throw new NoSuchElementException("队列为空！无法获取数据！");
        }

        int outElement = array[font];
        font = (font + 1)%array.length;

        return outElement;
    }

    public void expandCapacity(){

        int[] newArray = new int[array.length * 2];

        if(newArray.length > 100){
            throw new IllegalArgumentException("不准栈的深度超过100");
        }

        //将原数组复制到新数组里
        for(int i = 0,n = 0;i < array.length;i++){//队尾可能在数组的中间
            if(i == rear){//因为队尾要留一空
                continue;
            }
            newArray[n++] = array[i];
        }

        array = newArray;
    }

    @Override
    public String toString() {
        String str = "[";
        //只遍历数组当中的元素个数
        for(int i = font;i != rear;i = (i + 1)%array.length){
            str += array[i];
            //当不是最后1个元素,需要加逗号
            if(i != rear - 1){
                str += ",";
            }
        }
        //最后加一个"]"结尾
        str += "]";
        return str;
    }
}

3.测试

TestArray.java

public class TestArray {

    public static void main(String[] args) {

        Queue queue = new Queue(3);

        queue.enQueue(1);
        queue.enQueue(2);
        queue.enQueue(3);
        queue.enQueue(4);
        queue.enQueue(5);

        System.out.println(queue);

        System.out.println("出队:");

        queue.outQueue();
        queue.outQueue();
        queue.outQueue();
        queue.outQueue();
        queue.outQueue();

        System.out.println(queue);
    }
}

 完