队列遵循先进先出原则

创建队列

首先我们需要创建自己的类, 来表示队列. 先从最基本的声明开始:

class Queue {
    constructor() {
        this.items = []
    }

// 添加元素
 enqueue = function(elem) {
      this.items.push(elem)
    }
 // 返回被删除的元素
   dequeue = function(){
      if(this.empty()){
        return 'this itmes is empty'
      } else {
        return this.items.shift()
      }
    }

    // 返回队列中最先添加的元素
    front = function(){
      return this.items[0]
    }

    // 判断队列中是否包含元素
    empty = function() {
       return this.items.length > 0 ? false : true 
     }

      // 返回队列包含的元素个数
      size = function() {
         return this.items.length 
      }
      // 打印队列元素
       print = function () {
          console.log(this.items.toString())
        }
}

 let queue = new Queue()
 queue.enqueue('a')
 queue.enqueue('b')
 queue.print()

优先队列

实现一个优先队列,有两种选项,设置优先级,然后在正确的位置添加元素; 或者用入列操作添加元素,然后按照优先级移除它们.
接下来我们看看它的实现

      function PriorityQueue() {
        let items = []
        function QueueElement(elem,priority) {
          this.elem = elem
          this.priority = priority
        }

        this.enqueue = function(elem,priority) {
          let queueElement = new QueueElement(elem,priority)

          let added = false
            for (let i = 0; i < items.length; i++) {
            if(queueElement.priority < items[i].priority) {
              items.splice(i,0,queueElement)
              added = true
              break;
            }
          }

          if(!added) {
            items.push(queueElement)
          }
        }

        this.print = function () {
          for (let i = 0; i < items.length; i++) {
            console.log(`${items[i].elem} - ${items[i].priority}`)
          }
        }
      }

      let priorityQueue = new PriorityQueue()
      priorityQueue.enqueue('John',2)
      priorityQueue.enqueue('Jack',1)
      priorityQueue.enqueue('Camila',1)
      priorityQueue.print()

循环队列 --- 击鼓传❀

 // 循环队列
      function hotPotato(nameList,num) {
        let queue = new Queue()
        for (let i = 0; i < nameList.length; i++) {
          queue.enqueue(nameList[i])
        }

        let eliminated = ''
        while (queue.size() > 1) {
          for (let i = 0; i < num; i++) {
            queue.enqueue(queue.dequeue())
          }

          eliminated = queue.dequeue()
          console.log(eliminated + 'out')
        }

        return queue.dequeue()
      }

      let names = ['a','b','c','d','e','f']
      // b c d e f a
      // c d e f a b
      // d e f a b c
      // e f a b c d
      // f a b c d e
      // a b c d e f
      // b c d e f a  b out

      // 新数组 c d e f a
      // d e f a c  i = 0
      // e f a c d  i = 1
      // f a c d e  i = 2
      // a c d e f  i = 3
      // c d e f a  i = 4
      // d e f a c  i = 5
      // e f a c d //  i = 6  e out
      let winner = hotPotato(names,7)
      console.log(winner)