JavaScript数据结构与算法(三) 优先级队列的实现

TypeScript方式实现源码

 // Queue类和PriorityQueue类实现上的区别是，要向PriorityQueue添加元素，需要创建一个特殊的元素。这个元素包含了要添加到队列的元素（它可以是任意类型）及在队列中的优先级
 class QueueElement {
     element;
     priority;
     constructor(element, priority) {
         this.element = element;
         this.priority = priority;
     }
 }
 class PriorityQueue {
     items = [];
     public enqueue(element, priority) {
         let queueElement = new QueueElement(element, priority);

         if (this.isEmpty()) {
             this.items.push(queueElement);
         } else {
             let added = false;
             for (let i = ; i < this.items.length; i++) {
                 if (queueElement.priority < this.items[i].priority) {
                     this.items.splice(i, , queueElement);
                     added = true;
                     break;
                 }
             }
             if (!added) {
                 this.items.push(queueElement);
             }
         }
     }
     public dequeue() {
         return this.items.shift();
     }
     public front() {
         return this.items[];
     }
     public isEmpty() {
         return this.items.length == ;
     }
     public clear() {
         this.items = [];
     }
     public size() {
         return this.items.length;
     }
     public print() {
         console.log(this.items.toString());
     }
 }
 // 使用方法
 let priorityQueue = new PriorityQueue();
 priorityQueue.enqueue('John', );
 priorityQueue.enqueue('Jack', );
 priorityQueue.enqueue('Camila', );
 priorityQueue.print();

 // 下图中可以看到每条命令的结果

JavaScript方式实现源码

 var QueueElement = (function () {
     function QueueElement(element, priority) {
         this.element = element;
         this.priority = priority;
     }
     return QueueElement;
 }());
 var PriorityQueue = (function () {
     function PriorityQueue() {
         this.items = [];
     }
     PriorityQueue.prototype.enqueue = function (element, priority) {
         var queueElement = new QueueElement(element, priority);
         if (this.isEmpty()) {
             this.items.push(queueElement);
         }
         else {
             var added = false;
             for (var i_1 = ; i_1 < this.items.length; i_1++) {
                 if (queueElement.priority < this.items[i_1].priority) {
                     this.items.splice(i_1, , queueElement);
                     added = true;
                     break;
                 }
             }
             if (!added) {
                 this.items.push(queueElement);
             }
         }
     };
     PriorityQueue.prototype.dequeue = function () {
         return this.items.shift();
     };
     PriorityQueue.prototype.front = function () {
         return this.items[];
     };
     PriorityQueue.prototype.isEmpty = function () {
         return this.items.length == ;
     };
     PriorityQueue.prototype.clear = function () {
         this.items = [];
     };
     PriorityQueue.prototype.size = function () {
         return this.items.length;
     };
     PriorityQueue.prototype.print = function () {
         console.log(this.items.toString());
     };
     return PriorityQueue;
 }());

代码角度解读：
    PriorityQueue对比Queue.PriorityQueue为每个队列元素包裹了一个对象，该对象用于优先级的标记，添加时会对队列中所有数据进行便利计算.其他使用接口一致
抽象：
    优先队列的应用场景非常多比如排队买票、地铁安检、飞机登机、任务计划、项目排期.等等都是队列,优先队列是对队列的扩展，比如排队买票只有一个窗口,出于人道主义,
老人与小朋友可以优先.这时优先队列便可以将他们安排到队列前面
总结：
    当Queue能解决应用场景问题时不推荐使用PriorityQueue，以此来优化内存开支