mirror of
https://github.com/TheAlgorithms/JavaScript.git
synced 2025-07-18 17:49:40 +08:00
81 lines
2.0 KiB
JavaScript
81 lines
2.0 KiB
JavaScript
/* Queue
|
|
* A Queue is a data structure that allows you to add an element to the end of
|
|
* a list and remove the item at the front. A queue follows a "First In First Out"
|
|
* system, where the first item to enter the queue is the first to be removed. This
|
|
* implementation uses an array to store the queue.
|
|
*/
|
|
|
|
// Functions: enqueue, dequeue, peek, view, length
|
|
|
|
var Queue = (function () {
|
|
// constructor
|
|
function Queue () {
|
|
// This is the array representation of the queue
|
|
this.queue = []
|
|
}
|
|
|
|
// methods
|
|
// Add a value to the end of the queue
|
|
Queue.prototype.enqueue = function (item) {
|
|
this.queue[this.queue.length] = item
|
|
}
|
|
|
|
// Removes the value at the front of the queue
|
|
Queue.prototype.dequeue = function () {
|
|
if (this.queue.length === 0) {
|
|
throw new Error('Queue is Empty')
|
|
}
|
|
|
|
var result = this.queue[0]
|
|
this.queue.splice(0, 1) // remove the item at position 0 from the array
|
|
|
|
return result
|
|
}
|
|
|
|
// Return the length of the queue
|
|
Queue.prototype.length = function () {
|
|
return this.queue.length
|
|
}
|
|
|
|
// Return the item at the front of the queue
|
|
Queue.prototype.peek = function () {
|
|
return this.queue[0]
|
|
}
|
|
|
|
// List all the items in the queue
|
|
Queue.prototype.view = function () {
|
|
console.log(this.queue)
|
|
}
|
|
|
|
return Queue
|
|
}())
|
|
|
|
// Implementation
|
|
var myQueue = new Queue()
|
|
|
|
myQueue.enqueue(1)
|
|
myQueue.enqueue(5)
|
|
myQueue.enqueue(76)
|
|
myQueue.enqueue(69)
|
|
myQueue.enqueue(32)
|
|
myQueue.enqueue(54)
|
|
|
|
myQueue.view()
|
|
|
|
console.log('Length: ' + myQueue.length())
|
|
console.log('Front item: ' + myQueue.peek())
|
|
console.log('Removed ' + myQueue.dequeue() + ' from front.')
|
|
console.log('New front item: ' + myQueue.peek())
|
|
console.log('Removed ' + myQueue.dequeue() + ' from front.')
|
|
console.log('New front item: ' + myQueue.peek())
|
|
myQueue.enqueue(55)
|
|
console.log('Inserted 55')
|
|
console.log('New front item: ' + myQueue.peek())
|
|
|
|
for (var i = 0; i < 5; i++) {
|
|
myQueue.dequeue()
|
|
myQueue.view()
|
|
}
|
|
|
|
// console.log(myQueue.dequeue()); // throws exception!
|