摘要：小鹿題目設(shè)計(jì)實(shí)現(xiàn)雙端隊(duì)列。你的實(shí)現(xiàn)需要支持以下操作構(gòu)造函數(shù)雙端隊(duì)列的大小為。獲得雙端隊(duì)列的最后一個(gè)元素。檢查雙端隊(duì)列是否為空。數(shù)組頭部刪除第一個(gè)數(shù)據(jù)。以上數(shù)組提供的使得更方便的對(duì)數(shù)組進(jìn)行操作和模擬其他數(shù)據(jù)結(jié)構(gòu)的操作，棧隊(duì)列等。

Time：2019/4/15
Title: Design Circular Deque
Difficulty: Medium
Author: 小鹿

Design your implementation of the circular double-ended queue (deque).

Your implementation should support following operations:

MyCircularDeque(k): Constructor, set the size of the deque to be k.

insertFront(): Adds an item at the front of Deque. Return true if the operation is successful.

insertLast(): Adds an item at the rear of Deque. Return true if the operation is successful.

deleteFront(): Deletes an item from the front of Deque. Return true if the operation is successful.

deleteLast(): Deletes an item from the rear of Deque. Return true if the operation is successful.

getFront(): Gets the front item from the Deque. If the deque is empty, return -1.

getRear(): Gets the last item from Deque. If the deque is empty, return -1.

isEmpty(): Checks whether Deque is empty or not.

isFull(): Checks whether Deque is full or not.

設(shè)計(jì)實(shí)現(xiàn)雙端隊(duì)列。
你的實(shí)現(xiàn)需要支持以下操作：

MyCircularDeque(k)：構(gòu)造函數(shù),雙端隊(duì)列的大小為k。
insertFront()：將一個(gè)元素添加到雙端隊(duì)列頭部。 如果操作成功返回 true。
insertLast()：將一個(gè)元素添加到雙端隊(duì)列尾部。如果操作成功返回 true。
deleteFront()：從雙端隊(duì)列頭部刪除一個(gè)元素。 如果操作成功返回 true。
deleteLast()：從雙端隊(duì)列尾部刪除一個(gè)元素。如果操作成功返回 true。
getFront()：從雙端隊(duì)列頭部獲得一個(gè)元素。如果雙端隊(duì)列為空，返回 -1。
getRear()：獲得雙端隊(duì)列的最后一個(gè)元素。 如果雙端隊(duì)列為空，返回 -1。
isEmpty()：檢查雙端隊(duì)列是否為空。
isFull()：檢查雙端隊(duì)列是否滿了。

Example:

MyCircularDeque circularDeque = new MycircularDeque(3); // set the size to be 3
circularDeque.insertLast(1);            // return true
circularDeque.insertLast(2);            // return true
circularDeque.insertFront(3);            // return true
circularDeque.insertFront(4);            // return false, the queue is full
circularDeque.getRear();              // return 2
circularDeque.isFull();                // return true
circularDeque.deleteLast();            // return true
circularDeque.insertFront(4);            // return true
circularDeque.getFront();            // return 4

Note:

All values will be in the range of [0, 1000].

The number of operations will be in the range of [1, 1000].

Please do not use the built-in Deque library.

▉ 算法思路

借助 Javascript 中數(shù)組中的 API 可快速實(shí)現(xiàn)一個(gè)雙向隊(duì)列。如：


arr.pop() : 刪除數(shù)組尾部最后一個(gè)數(shù)據(jù)。

arr.push() ：在數(shù)組尾部插入一個(gè)數(shù)據(jù)。

arr.shift()：數(shù)組頭部刪除第一個(gè)數(shù)據(jù)。

arr.unshift()：數(shù)組頭部插入一個(gè)數(shù)據(jù)。

以上數(shù)組提供的 API 使得更方便的對(duì)數(shù)組進(jìn)行操作和模擬其他數(shù)據(jù)結(jié)構(gòu)的操作，棧、隊(duì)列等。

▉ 代碼實(shí)現(xiàn)

 //雙端列表構(gòu)造
        var MyCircularDeque = function(k) {
            this.deque = [];
            this.size = k;
        };

        /**
        * Adds an item at the front of Deque. Return true if the operation is successful. 
        * @param {number} value
        * @return {boolean}
        * 功能:隊(duì)列頭部入隊(duì)
        */
        MyCircularDeque.prototype.insertFront = function(value) {
            if(this.deque.length === this.size){
                return false;
            }else{
                this.deque.unshift(value);
                return true;
            }
        };

        /**
        * Adds an item at the rear of Deque. Return true if the operation is successful. 
        * @param {number} value
        * @return {boolean}
        * 功能：隊(duì)列尾部入隊(duì)
        */
        MyCircularDeque.prototype.insertLast = function(value) {
            if(this.deque.length === this.size){
                return false;
            }else{
                this.deque.push(value);
                return true;
            }
        };

        /**
        * Deletes an item from the front of Deque. Return true if the operation is successful.
        * @return {boolean}
        * 功能：隊(duì)列頭部出隊(duì)
        */
        MyCircularDeque.prototype.deleteFront = function() {
            if(this.deque.length === 0){
                return false;
            }else{
                this.deque.shift();
                return true;
            }
        };

        /**
        * Deletes an item from the rear of Deque. Return true if the operation is successful.
        * @return {boolean}
        * 功能：隊(duì)列尾部出隊(duì)
        */
        MyCircularDeque.prototype.deleteLast = function() {
            if(this.deque.length === 0){
                return false;
            }else{
                this.deque.pop();
                return true;
            }
        };

        /**
        * Get the front item from the deque.
        * @return {number}
        * 功能：獲取隊(duì)列頭部第一個(gè)數(shù)據(jù)
        */
        MyCircularDeque.prototype.getFront = function() {
            if(this.deque.length === 0){
                return -1;
            }else{
                return this.deque[0];
            }
        };

        /**
        * Get the last item from the deque.
        * @return {number}
        * 功能：獲取隊(duì)列尾部第一個(gè)數(shù)據(jù)
        */
        MyCircularDeque.prototype.getRear = function() {
            if(this.deque.length === 0){
                return -1;
            }else{
                return this.deque[this.deque.length - 1];
            }
        };

        /**
        * Checks whether the circular deque is empty or not.
        * @return {boolean}
        * 功能：判斷雙端隊(duì)列是否為空
        */
        MyCircularDeque.prototype.isEmpty = function() {
            if(this.deque.length === 0){
                return true;
            }else{
                return false;
            }
        };

        /**
        * Checks whether the circular deque is full or not.
        * @return {boolean}
        * 功能：判斷雙端隊(duì)列是否為滿
        */
        MyCircularDeque.prototype.isFull = function() {
            if(this.deque.length === this.size){
                return true;
            }else{
                return false;
            }
        };

        //測(cè)試
        var obj = new MyCircularDeque(3)
        var param_1 = obj.insertFront(1)
        var param_2 = obj.insertLast(2)
        console.log("-----------------------------插入數(shù)據(jù)------------------------")
        console.log(`${param_1}${param_2}`)
        var param_3 = obj.deleteFront()
        var param_4 = obj.deleteLast()
        console.log("-----------------------------刪除數(shù)據(jù)------------------------")
        console.log(`${param_3}${param_4}`)
        var param_5 = obj.getFront()
        var param_6 = obj.getRear()
        console.log("-----------------------------獲取數(shù)據(jù)------------------------")
        console.log(`${param_5}${param_6}`)
        var param_7 = obj.isEmpty()
        var param_8 = obj.isFull()
        console.log("-----------------------------判斷空/滿------------------------")
        console.log(`${param_7}${param_8}`)