0232-implement-queue-using-stacks.js

/**
 * 232. Implement Queue using Stacks
 * https://leetcode.com/problems/implement-queue-using-stacks/
 * Difficulty: Easy
 *
 * Implement a first in first out (FIFO) queue using only two stacks.
 * The implemented queue should support all the functions of a normal
 * queue (push, peek, pop, and empty).
 *
 * Implement the MyQueue class:
 * - void push(int x) Pushes element x to the back of the queue.
 * - int pop() Removes the element from the front of the queue and returns it.
 * - int peek() Returns the element at the front of the queue.
 * - boolean empty() Returns true if the queue is empty, false otherwise.
 */


var MyQueue = function() {
  this.data = [];
};

/**
 * @param {number} x
 * @return {void}
 */
MyQueue.prototype.push = function(x) {
  this.data.push(x);
};

/**
 * @return {number}
 */
MyQueue.prototype.pop = function() {
  return this.data.shift();
};

/**
 * @return {number}
 */
MyQueue.prototype.peek = function() {
  return this.data[0];
};

/**
 * @return {boolean}
 */
MyQueue.prototype.empty = function() {
  return !this.data.length;
};

/**
 * Your MyQueue object will be instantiated and called as such:
 * var obj = new MyQueue()
 * obj.push(x)
 * var param_2 = obj.pop()
 * var param_3 = obj.peek()
 * var param_4 = obj.empty()
 */