Каким будет код для реализации оптимизированной версии queue в C++?

#include <iostream>
#include <cassert>
#define MAX 5

using namespace std;

class queue{
public:
    queue();
    void Enqueue(int);
    int Dequeue();
    int size() const;
    bool isEmpty() const;

private:
    int arr[MAX];
    int sz;
    int front_idx,back_idx;
};

queue :: queue(){
    sz = 0;
    front_idx = 0;
    back_idx = 0;
}

void queue :: Enqueue(int val){
    if(sz == 5){
        //Queue Overflow
        assert("");
    }
    else{
        arr[back_idx] = val;
        sz++;
        back_idx = (back_idx + 1) % MAX;
    }
}

int queue :: Dequeue(){
    if(sz == 0){
        //Queue Underflow.
        assert("");
    }
    else{
        int ret_val = arr[front_idx];
        front_idx = (front_idx+1) % MAX;
        sz--;
        return ret_val;
    }
}

int queue :: size() const{
    return sz;
}

bool queue :: isEmpty() const{
    return (sz == 0);
}

int main()
{
    queue q;
    q.Enqueue(5);
    q.Enqueue(3);
    q.Enqueue(2);

    printf("%d\n",q.Dequeue());
    printf("%d\n",q.Dequeue());
    q.Enqueue(1);
    printf("%d\n",q.Dequeue());
    printf("%d\n",q.Dequeue());

}