QueueUsing2Stacks.js

// implementation of Queue using 2 stacks
// contribution made by hamza chabchoub for a university project

class Queue {
 constructor() {
 this.inputStack = []
 this.outputStack = []
 }

 // Push item into the inputstack
 enqueue(item) {
 this.inputStack.push(item)
 }

 dequeue() {
 // push all items to outputstack
 this.outputStack = []
 while (this.inputStack.length > 0) {
 this.outputStack.push(this.inputStack.pop())
 }
 // return the top element of the outputstack if any
 if (this.outputStack.length > 0) {
 const top = this.outputStack.pop()
 // repush all the items to the inputstack
 this.inputStack = []
 while (this.outputStack.length > 0) {
 this.inputStack.push(this.outputStack.pop())
 }
 return top
 }
 }

 // display elements of the inputstack
 listIn(output = (value) => console.log(value)) {
 let i = 0
 while (i < this.inputStack.length) {
 output(this.inputStack[i])
 i++
 }
 }

 // display element of the outputstack
 listOut(output = (value) => console.log(value)) {
 let i = 0
 while (i < this.outputStack.length) {
 output(this.outputStack[i])
 i++
 }
 }
}

export { Queue }