content: /**
   * File: array_stack.dart
   * Created Time: 2023-03-28
   * Author: liuyuxin (gvenusleo@gmail.com)
   */
  
  /* 基于数组实现的栈 */
  class ArrayStack {
    late List<int> _stack;
    ArrayStack() {
      _stack = [];
    }
  
    /* 获取栈的长度 */
    int size() {
      return _stack.length;
    }
  
    /* 判断栈是否为空 */
    bool isEmpty() {
      return _stack.isEmpty;
    }
  
    /* 入栈 */
    void push(int _num) {
      _stack.add(_num);
    }
  
    /* 出栈 */
    int pop() {
      if (isEmpty()) {
        throw Exception("栈为空");
      }
      return _stack.removeLast();
    }
  
    /* 访问栈顶元素 */
    int peek() {
      if (isEmpty()) {
        throw Exception("栈为空");
      }
      return _stack.last;
    }
  
    /* 将栈转化为 Array 并返回 */
    List<int> toArray() => _stack;
  }
  
  /* Driver Code */
  void main() {
    /* 初始化栈 */
    final ArrayStack stack = ArrayStack();
  
    /* 元素入栈 */
    stack.push(1);
    stack.push(3);
    stack.push(2);
    stack.push(5);
    stack.push(4);
    print("栈 stack = ${stack.toArray()}");
  
    /* 访问栈顶元素 */
    final int peek = stack.peek();
    print("栈顶元素 peek = $peek");
  
    /* 元素出栈 */
    final int pop = stack.pop();
    print("出栈元素 pop = $pop ，出栈后 stack = ${stack.toArray()}");
  
    /* 获取栈的长度 */
    final int size = stack.size();
    print("栈的长度 size = $size");
  
    /* 判断是否为空 */
    final bool isEmpty = stack.isEmpty();
    print("栈是否为空 = $isEmpty");
  }
  