=begin
File: array_stack.rb
Created Time: 2024-04-06
Author: Xuan Khoa Tu Nguyen (ngxktuzkai2000@gmail.com)
=end

### 基于数组实现的栈 ###
class ArrayStack
  ### 构造方法 ###
  def initialize
    @stack = []
  end

  ### 获取栈的长度 ###
  def size
    @stack.length
  end

  ### 判断栈是否为空 ###
  def is_empty?
    @stack.empty?
  end

  ### 入栈 ###
  def push(item)
    @stack << item
  end

  ### 出栈 ###
  def pop
    raise IndexError, '栈为空' if is_empty?

    @stack.pop
  end

  ### 访问栈顶元素 ###
  def peek
    raise IndexError, '栈为空' if is_empty?

    @stack.last
  end

  ### 返回列表用于打印 ###
  def to_array
    @stack
  end
end

### Driver Code ###

# 初始化栈
stack = ArrayStack.new

# 元素入栈
stack.push(1)
stack.push(3)
stack.push(2)
stack.push(5)
stack.push(4)
puts "栈 stack = #{stack.to_array}"

# 访问栈顶元素
peek = stack.peek
puts "栈顶元素 peek = #{peek}"

# 元素出栈
pop = stack.pop
puts "出栈元素 pop = #{pop}"
puts "出栈后 stack = #{stack.to_array}"

# 获取栈的长度
size = stack.size
puts "栈的长度 size = #{size}"

# 判断是否为空
is_empty = stack.is_empty?
puts "栈是否为空 = #{is_empty}"