Commit fa2a68a

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update: queue using stack

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Original file line number	Diff line number	Diff line change
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	`1`	`+const Stack = require('../../Stack');`
	`2`	`+`
	`3`	`+class Queue {`
	`4`	`+ constructor() {`
	`5`	`+ this.queue = new Stack();`
	`6`	`+ this.temp = new Stack();`
	`7`	`+ }`
	`8`	`+`
	`9`	`+ enqueue(data) {`
	`10`	`+ this.queue.push(data);`
	`11`	`+ }`
	`12`	`+`
	`13`	`+ dequeue() {`
	`14`	`+ if (!this.queue.peek()) {`
	`15`	`+ return null;`
	`16`	`+ }`
	`17`	`+`
	`18`	`+ // pop all the element to the temp stack`
	`19`	`+ while (this.queue.peek()) this.temp.push(this.queue.pop());`
	`20`	`+ const el = this.temp.pop();`
	`21`	`+`
	`22`	`+ // push all the temp items to the queue again`
	`23`	`+ while (this.temp.peek()) this.queue.push(this.temp.pop());`
	`24`	`+ return el;`
	`25`	`+ }`
	`26`	`+}`
	`27`	`+`
	`28`	`+module.exports = Queue;`

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