자바스크립트 Queue

class Queue {
	constructor () {
    	this.queue = [];
        this.front = 0;
        this.rear = 0;
    }
    
    enqueue(value
    	this.queue[this.rear++] = value;
    }
    
    dequeue(){
    	cosnt value = this.queue[this.front];
        delete this.queue[this.front];
        this.front += 1
        return value
    }
    peek(){
    	return this.queue[this.front]
        
    }
    
    size(){
    	return this.rear - this.front
    }
}

Linked List

class Node {
	constructor(value){
    	this.value = value;
        this.next = null;
    }

}

class Queue {
	constructor() {
    	this.head = null;
        this.tail = null;
        this.size= 0;
    }
    
    enqueue(newValue) {
    	const newNode  = new Node(newValue);
        if (this.head === null) {
        	this.head = this.tail = newNode;
        } else {
        	this.tail.next = newNode;
            this.tail = newNode;
        }
        this.size += 1;
    }
    
    dequeue() {
    	const value = this.head.value;
        this.head = this.head.next;
        this.size -= 1;
        return value
    }
    peek() {
    	return this.head.value
    }
}

shift 사용하지말것 
자바스크립트에서 shift는 선형시간이 소요되기 때문에 x
const queue = [1,2,3];
queue.push(4);
const value = queue.shift() // O(n)!
console.log(value)