js算法练习--队

 //一般队列
        class queue {
            constructor() {
                this.list = [];
            }

            //入队
            EnQueue(item) {
                this.list.push(item);
            }
            //出队
            Dequeue() {
                return this.list.shift();
            }
            //第一个元素值
            GetFront() {
                return this.list[0];
            }
            //长度
            GetSize() {
                return this.list.length;
            }
            //是否为空
            GetIsEmpty() {
                return this.list.length == 0;
            }
            // 清空
            Clear() {
                this.list = [];
            }
            //读取元素
            Read() {
                console.log(this.list.toString());
            }
        }

        let queueTest = new queue();
        queueTest.GetIsEmpty();//true
        queueTest.EnQueue(1);
        queueTest.EnQueue(2);
        queueTest.EnQueue(3);
        queueTest.Read();//1,2,3
        queueTest.Dequeue();//1
        queueTest.Read();//2,3

        //优先队列：1：老年人和孕妇(或 带小孩的妇女)登机时也享有高于其他乘客的优先级；
        //医生会优先处理病情比较严重的患者
        class PriorityQueue {
            constructor() {
                this.list = [];
            }

            //入队
            EnQueue(item, priority) {
                var f = { item: item, index: priority };
                if (this.list.length == 0)
                    this.list.push(f);
                else {
                    var position = this.list.findIndex(x => x.index > f.index);
                    if (position == -1)
                        this.list.push(f);
                    else
                        this.list.splice(position, 0, f);
                }
            }
            //出队
            Dequeue() {
                return this.list.shift();
            }
            //第一个元素值
            GetFront() {
                return this.list[0];
            }
            //长度
            GetSize() {
                return this.list.length;
            }
            //是否为空
            GetIsEmpty() {
                return this.list.length == 0;
            }
            // 清空
            Clear() {
                this.list = [];
            }
            //读取元素
            Read() {
                console.log(this.list);
            }
        }
        var priorityQueue = new PriorityQueue();
        priorityQueue.GetIsEmpty();//true;
        priorityQueue.EnQueue(1, 1);
        priorityQueue.EnQueue(2, 2);
        priorityQueue.EnQueue(22, 3);
        priorityQueue.EnQueue(22, 5);
        priorityQueue.Read();//[{item:1,index:1},{item:2,index:2},{item:22,index:3},{item:22,index:5}]
        priorityQueue.EnQueue(33, 4);
        priorityQueue.Read();//[{item:1,index:1},{item:2,index:2},{item:22,index:3},{item:22,index:4},{item:22,index:5}]
        priorityQueue.Dequeue();//{item:1,index:1}
        //循环队列
        //为充分利用向量空间，克服"假溢出"现象的方法是：将向量空间想象为一个首尾相接的圆环，并称这种向量为循环向量。
        class LoopQueue extends queue {

            constructor(items) {
                super(items)
            }

            getIndex(index) {
                const length = this.list.length
                return index > length ? (index % length) : index
            }

            find(index) {
                return !this.isEmpty ? this.list[this.getIndex(index)] : null
            }
        }
        var loopQueue=new LoopQueue();
        loopQueue.EnQueue(1);
        loopQueue.EnQueue(2);
        loopQueue.EnQueue(3);
        loopQueue.Read();//1,2,3
        loopQueue.find(7);//2