Implement Stack using Queues Problem & Solution

#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx,avx2,fma")
#pragma GCC ivdep

static const int _=[]{ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();

class MyStack {
public:
  MyStack() {
    // noop
  }

  void push(int x) {
    q.push(x);
  }

  int pop() {
    queue<int> w;

    while (!q.empty()) {
      int top = q.front();
      q.pop();

      w.push(top);
    }

    while (w.size() > 1) {
      int top = w.front();
      w.pop();

      q.push(top);
    }

    return w.front();
  }

  int top() {
    return q.back();
  }

  bool empty() {
    return q.empty();
  }

private:
  queue<int> q;
};