hello-algo/codes/kotlin/chapter_stack_and_queue/array_stack.kt

/**
 * File: array_stack.kt
 * Created Time: 2024-01-25
 * Author: curtishd (1023632660@qq.com)
 */

package chapter_stack_and_queue

/* 基于数组实现的栈 */
class ArrayStack {
    // 初始化列表（动态数组）
    private val stack = mutableListOf<Int>()

    /* 获取栈的长度 */
    fun size(): Int {
        return stack.size
    }

    /* 判断栈是否为空 */
    fun isEmpty(): Boolean {
        return size() == 0
    }

    /* 入栈 */
    fun push(num: Int) {
        stack.add(num)
    }

    /* 出栈 */
    fun pop(): Int {
        if (isEmpty()) throw IndexOutOfBoundsException()
        return stack.removeAt(size() - 1)
    }

    /* 访问栈顶元素 */
    fun peek(): Int {
        if (isEmpty()) throw IndexOutOfBoundsException()
        return stack[size() - 1]
    }

    /* 将 List 转化为 Array 并返回 */
    fun toArray(): Array<Any> {
        return stack.toTypedArray()
    }
}

/* Driver Code */
fun main() {
    /* 初始化栈 */
    val stack = ArrayStack()

    /* 元素入栈 */
    stack.push(1)
    stack.push(3)
    stack.push(2)
    stack.push(5)
    stack.push(4)
    println("栈 stack = ${stack.toArray().contentToString()}")

    /* 访问栈顶元素 */
    val peek = stack.peek()
    println("栈顶元素 peek = $peek")

    /* 元素出栈 */
    val pop = stack.pop()
    println("出栈元素 pop = $pop，出栈后 stack = ${stack.toArray().contentToString()}")

    /* 获取栈的长度 */
    val size = stack.size()
    println("栈的长度 size = $size")

    /* 判断是否为空 */
    val isEmpty = stack.isEmpty()
    println("栈是否为空 = $isEmpty")
}