《数据结构与算法Javascript描述》第五章 队列 习题答案

   function Queue() {
            this.dataStore = [];
            this.enqueue = enqueue;
            this.dequeue = dequeue;
            this.fornt = front;
            this.back = back;
            this.toString = toString;
            this.empty = empty;
            this.count = count;
        }

        function enqueue(element) {
            this.dataStore.push(element);
        }

        function dequeue() {
            return this.dataStore.shift();
        }

        function front() {
            return this.dataStore[0];
        }

        function back() {
            return this.dataStore[this.dataStore.length - 1]
        }

        function toString() {
            var reStr = '';
            for (let i = 0; i < this.dataStore.length; i++) {
                reStr += this.dataStore[i]
            }

            return reStr
        }

        function empty() {
            if (this.dataStore.length == 0) {
                return true
            } else {
                return false
            }
        }

        function count() {
            return this.dataStore.length;
        }

1. 修改queue类，形成Deque类，允许队列两端添加和删除元素，也叫双向队列
   2.使Deque类来判定一个给定的单词是否为回文

 function Deque() {
        }

        Deque.prototype = new Queue();

        // l:left r:right
        Deque.prototype.enqueue = function (element, direction) {
            var _this = this;
            switch (direction) {
                case 'l':
                    _this.dataStore.unshift(element)
                    break;
                case 'r':
                    _this.dataStore.push(element)
                    break;
                default:
                    _this.dataStore.push(element);
            }
        }


        Deque.prototype.dequeue = function (direction) {
            var _this = this;
            switch (direction) {
                case 'l':
                    _this.dataStore.shift()
                    break;
                case 'r':
                    _this.dataStore.pop()
                    break;
            }
        }


        function test(word) {
            var l = new Deque();
            l.dataStore = [];
            var r = new Deque();
            r.dataStore = [];
            for (let i = 0; i < word.length; i++) {
                l.enqueue(word[i], 'l')
                r.enqueue(word[i], 'r')

            }
            if (l.toString() == r.toString()) {
                return true
            } else {
                return false
            }
        }
        console.log(test('hahaa')) //false
        console.log(test('haah')) //true

2. 优先级高的优先码也大

 function Patient(name, code) {
            this.name = name;
            this.code = code;
        }

        var PriorQueue = function () { }
        PriorQueue.prototype = new Queue();
        PriorQueue.prototype.dequeue = function () {
            var max = this.dataStore[0].code;
            var index = 0;
            for (let i = 0; i < this.dataStore.length; i++) {
                if (max < this.dataStore[i].code) {
                    max = this.dataStore[i].code;
                    index = i
                }
            }
            return this.dataStore.splice(index, 1)
        }
        var priorQueue = new PriorQueue();
        priorQueue.enqueue(new Patient('张三', 10));
        priorQueue.enqueue(new Patient('张三1', 3));
        priorQueue.enqueue(new Patient('张三2', 11));
        priorQueue.enqueue(new Patient('张三3', 23));
        priorQueue.enqueue(new Patient('张三4', 1));
        console.log(priorQueue.dequeue());

3. 控制候诊室内活动 a).患者进入候诊室 b).患者就诊 c.)显示等待就诊患者名单

 var visits = function () {
        }
        visits.prototype = new PriorQueue();
        visits.prototype.in = function (p) {
            this.enqueue(p)
        }

        visits.prototype.vist = function () {
            this.dequeue()
        }

        visits.prototype.show = function () {
            return this.dataStore
        }
        var visites = new visits();
        visites.in(new Patient('张三', 10));
        visites.in(new Patient('张三1', 3));
        visites.in(new Patient('张三2', 11));
        visites.in(new Patient('张三3', 23));
        visites.in(new Patient('张三4', 1));


        console.log(visites.dequeue())
        console.log(visites.show())