232.Implement_Queue_using_Stacks.js

/**
 * Initialize your data structure here.
 * 性能：56ms 92.29% 33.5MB 100%
 */

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

/**
 * Push element x to the back of queue.
 * @param {number} x
 * @return {void}
 */
MyQueue.prototype.push = function (x) {
  this.queue.push(x);
};

/**
 * Removes the element from in front of queue and returns that element.
 * @return {number}
 */
MyQueue.prototype.pop = function () {
  return this.queue.shift();
};

/**
 * Get the front element.
 * @return {number}
 */
MyQueue.prototype.peek = function () {
  return this.queue[0];
};

/**
 * Returns whether the queue is empty.
 * @return {boolean}
 */
MyQueue.prototype.empty = function () {
  return this.queue.length === 0;
};

/**
 * 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()
 */