关于javascript:JavaScript数据结构杂谈双端队列

双端队列是与队列相似的项的有序汇合，其实实质就是队列，只不过是前端与后端都反对插入和删除操作的队列，更实用，所以也就不存在先进先出这种说法了。

咱们能够通过数组来实现，然而为了写出一个更高效得数据结构，应用对象来实现。

class Deque{constructor(){
        this.count= 0;
        this.lowestCount = 0;
        this.items = {};}
    isEmptry(){return this.size() === 0;
    }
    size(){return this.count - this.lowestCount;}
    clear(){
        this.count= 0;
        this.lowestCount = 0;
        this.items = {};}
    toString(){if(this.isEmptry()){return '';}
        let objString = `${this.items[this.lowestCount]}`;
        for (let i=this.lowestCount+1;i<this.count;i++) {objString = `${objString},${this.items[i]}`;
        }
        return objString;
    }
    addBack(el){this.item[this.count]=el;
        this.count++;
    }
    addFront(el){if(this.isEmptry()){this.addBack(el);
        }else if(this.lowestCount>0){
            this.lowestCount--;
            this.item[this.lowestCount]=el;
        }else{for(let i=this.count;i>0;i--){this.item[i]=this.item[i-1];
            }
            this.count++;
            this.lowestCount=0;
            this.item[0]=el;
        }
    }
    removeFront(){if(this.isEmptry()){return undefined;}
        let c = this.items[this.lowestCount];
        delete this.items[this.lowestCount];
        this.lowestCount++;
        return c;
    }
    removeBack(){if (this.isEmpty()) {return undefined;}
         this.count--;
         let c = this.items[this.count];
         delete this.items[this.count];
         return c;
    }
    peekFront() {if (this.isEmpty()) {return undefined;}
        return this.items[this.lowestCount];
    }
    peekBack() {if (this.isEmpty()) {return undefined;}
        return this.items[this.count - 1];
    }
 }

该内容借鉴于学习 javascript 数据结构与算法。