简单的Stack实现

简单的 Stack 实现

数组实现

class Stack {
  constructor(size = 10) {
    this.arr = [] // 栈
    this.size = size // 最大长度
    this.top = -1 // 栈顶
  }

  push(elem) {
    if (this.top == this.size) {
      this.size *= 2
    }
    this.arr[++this.top] = elem
    return true
  }

  pop() {
    let elem = this.arr[this.top--]
    return elem
  }

  peekTop() {
    if (this.top == -1) {
      console.log("stack is empty")
      return
    }
    return this.arr[this.top]
  }

  print() {
    let str = ""
    for (let i = 0; i <= this.top; i++) {
      str += this.arr[i] + " "
    }
    console.log(str)
  }
}
var stack = new Stack()
stack.push(1)
stack.push(2)
stack.pop()
console.log(stack.peekTop())

链式实现

class Node {
  constructor(data = -1, next = null) {
    this.data = data
    this.next = next
  }
}
class Stack {
  constructor() {
    this.top = null // 栈顶
    this.elems = 0 // 成员个数
  }

  push(elem) {
    this.top = new Node(elem, this.top)
    this.elems++
  }

  pop() {
    if (this.elems == 0) {
      console.log("stack is empty")
      return
    }
    let current = this.top
    let elem = current.data
    this.top = this.top.next
    this.elems--
    current = null
    return elem
  }

  peekTop() {
    return this.top.data
  }
}

结果：

1