2017-09-28 10:52:12 -04:00
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/* Queue
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* A Queue is a data structure that allows you to add an element to the end of
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* a list and remove the item at the front. A queue follows a "First In First Out"
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* system, where the first item to enter the queue is the first to be removed. This
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* implementation uses an array to store the queue.
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*/
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2020-05-03 09:05:12 +02:00
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// Functions: enqueue, dequeue, peek, view, length
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2017-09-28 10:52:12 -04:00
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2020-10-31 12:03:11 +05:30
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const Queue = (function () {
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2018-03-30 16:04:27 +02:00
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// constructor
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2020-05-03 09:05:12 +02:00
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function Queue () {
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// This is the array representation of the queue
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this.queue = []
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2018-03-30 16:03:13 +02:00
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}
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2017-09-28 10:52:12 -04:00
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2020-05-03 09:05:12 +02:00
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// methods
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// Add a value to the end of the queue
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2018-03-30 16:03:13 +02:00
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Queue.prototype.enqueue = function (item) {
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2020-10-27 02:59:07 +06:00
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this.queue.push(item)
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2020-05-03 09:05:12 +02:00
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}
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2017-09-28 10:52:12 -04:00
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2020-05-03 09:05:12 +02:00
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// Removes the value at the front of the queue
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2018-03-30 16:03:13 +02:00
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Queue.prototype.dequeue = function () {
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2017-10-01 20:24:25 -04:00
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if (this.queue.length === 0) {
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2020-05-03 21:26:52 -03:00
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throw new Error('Queue is Empty')
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2017-09-28 10:52:12 -04:00
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}
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2020-10-31 12:03:11 +05:30
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const result = this.queue[0]
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2020-05-03 09:05:12 +02:00
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this.queue.splice(0, 1) // remove the item at position 0 from the array
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2017-09-28 10:52:12 -04:00
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2020-05-03 09:05:12 +02:00
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return result
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}
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2017-09-28 10:52:12 -04:00
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2020-05-03 09:05:12 +02:00
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// Return the length of the queue
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2018-03-30 16:03:13 +02:00
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Queue.prototype.length = function () {
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2020-05-03 09:05:12 +02:00
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return this.queue.length
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}
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2017-09-28 10:52:12 -04:00
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2020-05-03 09:05:12 +02:00
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// Return the item at the front of the queue
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2018-03-30 16:03:13 +02:00
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Queue.prototype.peek = function () {
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2020-05-03 09:05:12 +02:00
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return this.queue[0]
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}
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2017-09-28 10:52:12 -04:00
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2020-05-03 09:05:12 +02:00
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// List all the items in the queue
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2018-03-30 16:03:13 +02:00
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Queue.prototype.view = function () {
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2020-05-03 09:05:12 +02:00
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console.log(this.queue)
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}
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2018-03-30 16:03:13 +02:00
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2020-05-03 09:05:12 +02:00
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return Queue
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}())
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2017-09-28 10:52:12 -04:00
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2020-05-03 09:05:12 +02:00
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// Implementation
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2020-10-27 02:59:07 +06:00
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const myQueue = new Queue()
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2017-09-28 10:52:12 -04:00
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2020-05-03 09:05:12 +02:00
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myQueue.enqueue(1)
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myQueue.enqueue(5)
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myQueue.enqueue(76)
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myQueue.enqueue(69)
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myQueue.enqueue(32)
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myQueue.enqueue(54)
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2017-09-28 10:52:12 -04:00
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2020-05-03 09:05:12 +02:00
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myQueue.view()
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2017-09-28 10:52:12 -04:00
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2020-10-27 02:59:07 +06:00
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console.log(`Length: ${myQueue.length()}`)
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console.log(`Front item: ${myQueue.peek()}`)
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console.log(`Removed ${myQueue.dequeue()} from front.`)
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console.log(`New front item: ${myQueue.peek()}`)
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console.log(`Removed ${myQueue.dequeue()} from front.`)
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console.log(`New front item: ${myQueue.peek()}`)
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2020-05-03 09:05:12 +02:00
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myQueue.enqueue(55)
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console.log('Inserted 55')
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2020-10-27 02:59:07 +06:00
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console.log(`New front item: ${myQueue.peek()}`)
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2017-09-28 10:52:12 -04:00
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2020-10-31 12:03:11 +05:30
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for (let i = 0; i < 5; i++) {
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2020-05-03 09:05:12 +02:00
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myQueue.dequeue()
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myQueue.view()
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2017-09-28 10:52:12 -04:00
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}
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2020-10-31 12:03:11 +05:30
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// console.log(myQueue.dequeue()); // throws exception!
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