数据结构_栈

//栈， 一种运算受限的线性表，后进先出(LIFO)
  class Stack {
    constructor () {
      this.items = []
    }
    // 进栈
    enterStack (elem) {
      return this.items.push(elem)
    }
    // 出栈
    outStack () {
      return this.items.pop()
    }
    // 查看栈顶元素，仅仅是查看元素，不进行任何操作
    peek () {
      return this.items[this.items.length - 1]
    }
    // 栈是否为空
    isEmpty () {
      return this.items.length <= 0
    }
    // 清空栈
    clear () {
      this.items = []
      return true
    }
    // 栈内元素个数
    size () {
      return this.items.length
    }
  }
  
  var stack = new Stack()
  stack.enterStack(0)
  stack.enterStack(1)
  stack.enterStack(2)
  stack.enterStack(3)
  stack.enterStack(4)
  stack.outStack()
  stack.peek()
  stack.isEmpty()
  stack.clear()
  stack.size()