232.cpp

// doubleStacks-0ms.cpp
class MyQueue {
  stack<int> in;
  stack<int> out;

public:
  /** Initialize your data structure here. */
  MyQueue() {}

  /** Push element x to the back of queue. */
  void push(int x) { in.push(x); }

  /** Removes the element from in front of queue and returns that element. */
  int pop() {
    if (out.empty()) {
      while (!in.empty()) {
        out.push(in.top());
        in.pop();
      }
    }
    int temp = out.top();
    out.pop();
    return temp;
  }

  /** Get the front element. */
  int peek() {

    if (out.empty()) {
      while (!in.empty()) {
        out.push(in.top());
        in.pop();
      }
    }
    return out.top();
  }

  /** Returns whether the queue is empty. */
  bool empty() { return in.empty() == 1 && out.empty() == 1; }
};

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