LeetCode / Design / 232번 / Implement Queue using Stacks / JS

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Implement Queue using Stacks - LeetCode

 

< 문제 간단설명 >

queue의 메소드인 push, peek, pop, empty를 두 개의 stack을 이용해서 구현한다.

 

var MyQueue = function () {
  this.stack1 = [];
  this.stack2 = [];
};

/**
 * @param {number} x
 * @return {void}
 */
MyQueue.prototype.push = function (x) {
  this.stack1.push(x);
};

/**
 * @return {number}
 */
MyQueue.prototype.pop = function () {
  if (this.stack2.length === 0) {
    while (this.stack1.length) {
      this.stack2.push(this.stack1.pop());
    }
  }

  return this.stack2.pop();
};

/**
 * @return {number}
 */
MyQueue.prototype.peek = function () {
  if (this.stack2.length === 0) {
    while (this.stack1.length) {
      this.stack2.push(this.stack1.pop());
    }
  }

  return this.stack2.at(-1);
};

/**
 * @return {boolean}
 */
MyQueue.prototype.empty = function () {
  return !this.stack1.length && !this.stack2.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()
 */