【Java数据结构】实现栈和队列

我不是女神ヾ 2024-04-03 09:09 89阅读 0赞

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> 专栏：[数据结构与算法][Link 2]
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![5c4dc6a786c2cf8641ee40fc0263daa9.jpeg][]

**栈：**

MyStack.java

public class MyStack {
        //栈的底层我们用数组存储数据
        int[] elements;
    
        public MyStack() {
            elements = new int[0];
        }
        //压入元素
        public void push(int element){
            //创建一个新数组
            int[] newArr = new int[elements.length + 1];
            //把原数组的值复制到新数组中
            for (int i = 0; i < elements.length; i++) {
                newArr[i] = elements[i];
            }
            //把添加的元素放入新数组中
            newArr[elements.length] = element;
            //使用新数组替换旧数组
            elements = newArr;
        }
        //取出栈顶元素
        public int pop(){
            if (elements.length ==0){
                throw new RuntimeException("stack is Empty");
            }
            //取出数组中最后一个元素
            int element = elements[elements.length-1];
            //创建一个新数组
            int[] newArr = new int[elements.length-1];
            for (int i = 0; i < elements.length-1; i++) {
                newArr[i] = elements[i];
            }
            elements = newArr;
            return element;
        }
        //查看栈顶元素
        public int peek(){
            return elements[elements.length-1];
        }
        //判断栈顶是否为空
        public boolean isEmpty(){
            return elements.length == 0;
        }
    }

Test.java

public class Test {
        public static void main(String[] args) {
            MyStack ms = new MyStack();
            ms.push(3);
            ms.push(6);
            ms.push(4);
            ms.push(45);
            System.out.println("栈顶元素是"+ms.peek());
            ms.pop();
            System.out.println("栈顶元素是"+ms.peek());
            System.out.println(ms.isEmpty());
        }
    
    }

测试结果：

![98675439730b45a3b2f3b2ed07cf7392.png][]

![514cf2ed925243189ee8c635a98db34d.png][]

**队列：**

MyQueue.java

public class MyQueue {
        int[] elements;
        public MyQueue() {
            elements = new int[0];
        }
        public void add(int element){
            int[] newArr = new int[elements.length+1];
            for (int i = 0; i < elements.length; i++) {
                newArr[i] = elements[i];
            }
            newArr[elements.length] = element;
            elements = newArr;
        }
        public int poll(){
            if (elements.length == 0){
                throw new RuntimeException("queue is Empty");
            }
            int element = elements[0];
            int[] newArr = new int[elements.length - 1];
            for (int i = 0; i < elements.length - 1; i++) {
                newArr[i] = elements[i+1];
            }
            elements = newArr;
            return element;
        }
        public boolean isEmpty(){
            return elements.length == 0;
        }
    
    }

Test.java

public class Test {
        public static void main(String[] args) {
            MyQueue mq = new MyQueue();
            mq.add(1);
            mq.add(4);
            mq.add(5);
            mq.add(45);
            System.out.println(mq.poll());
            System.out.println(mq.poll());
            System.out.println(mq.poll());
            System.out.println(mq.poll());
            System.out.println(mq.isEmpty());
    
        }
    
    
    }

测试结果：

![ed70f521570241f3b1e525ef09c821ec.png][]

[ced485cbb11e458d81a746890b32cf3f.gif]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/03/3e42366fbda3480b97e12a912dae9be1.gif
[Link 1]: https://blog.csdn.net/m0_67995737?type=blog
[Link 2]: https://blog.csdn.net/m0_67995737/category_12000344.html
[Link 3]: https://www.nowcoder.com/link/pc_csdncpt_ylcxx_c
[5c4dc6a786c2cf8641ee40fc0263daa9.jpeg]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/03/9ebc8679a9514d70bd6c3f5a81c10f13.jpeg
[98675439730b45a3b2f3b2ed07cf7392.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/03/f4f677d449b2406ea91a5d47ee5cbff7.png
[514cf2ed925243189ee8c635a98db34d.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/03/118a773b90db4ba48b4de98aee5f9f08.png
[ed70f521570241f3b1e525ef09c821ec.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/03/a1c7246fe13a45be8931a59894f35161.png