Java数据结构与算法_栈

一、栈简介

栈（stack）是限制插入和删除只能在一个位置上进行的表，该位置是表的末端，叫做栈顶（top）。它是后进先出（LIFO）的。对栈的基本操作只有push（进栈）和pop（出栈）两种，前者相当于插入，后者相当于删除最后的元素。

二、栈的Java实现

/**
 * @Author: slx
 * @Date: 2019/5/9 18:37
 */
public class ShuStack {
    private int[] array;
    private int maxSize;
    private int top;

    public ShuStack(int maxSize) {
        this.maxSize = maxSize;
        array = new int[maxSize];
        top = -1;
    }

    //压入元素
    public void push(int value) {
        if (top < maxSize-1) {
            array[++top] = value;
        }
    }

    //弹出栈顶元素
    public int pop() {
        return array[top--];
    }

    //访问栈顶元素
    public int peek() {
        return array[top];
    }

    //判断栈是否为空
    public boolean isEmpty() {
        return (top == -1);
    }

    //判断栈是否满了
    public boolean isFull() {
        return (top == maxSize-1);
    }
}

测试代码：

/**
 * @Author: slx
 * @Date: 2019/5/9 18:48
 */
public class ShuStackTest {
    public static void main(String[] args) {
        ShuStack stack = new ShuStack(4);
        stack.push(10);
        stack.push(20);
        stack.push(30);
        System.out.println(stack.peek());
        while(!stack.isEmpty()) {
            System.out.print(stack.pop() + " " );
        }
    }
}

结果：

30
30 20 10 
Process finished with exit code 0

三、栈的应用：单词逆序

import java.util.Stack;
/**
 * @Author: slx
 * @Date: 2019/5/9 18:42
 */
public class TestStringReverse {
    public static void main(String[] args) {
        Stack stack = new Stack();
        String str = "shu push";
        char[] chars = str.toCharArray();
        for (char c : chars) {
            stack.push(c);
        }
        for (int i = 0; i < str.length(); i++) {
            System.out.print(stack.peek());
            stack.pop();
        }
    }
}

结果：

hsup uhs
Process finished with exit code 0