class Queue {

constructor() {

this.data = []

this.head = 0

this.count = 0

}

/**

* Building Queue of array by array

* @param {Array} array

*/

build(array) {

this.data = array

this.count = array.length

}

/**

* Get Queue's length.

* @returns {number}

*/

get size() {

return this.count

}

/**

* @returns {boolean}

*/

isEmpty() {

return !this.count

}

/**

* Add a new element to the end.

* @param item

*/

enqueue(item) {

this.data[this.head + this.count] = item

this.count++

}

/**

* The element in front of the queue will removed and returned.

* @returns {null|*}

*/

dequeue() {

if (this.count <= 0) return null

const element = this.data[this.head]

this.head++

this.count--

return element

}

}

module.exports = {

Queue

}