#include <assert.h>
#include <iostream>
#include <utility>

class array {
    int *data{nullptr};
    size_t n{0};
public:
    ~array() { delete [] data; }
    array() : array(0) {}
    array(const array &obj) {
        data = new int[obj.n];
        n = obj.n;
        for (size_t i = 0; i < n; i++)
        {
            data[i] = obj.data[i];
        }
    }
    explicit array(size_t m) {
        if (m == 0) m = 10;
        n = m;
        data = new int[n];
        for (size_t i = 0; i < n; i++)
        {
            data[i] = 0;
        } 
    }
    array(int *p, size_t count) {
        if (p != nullptr && count != 0) {
            data = p;
            n = count;
        } else {
            // copy-and-swap
            auto tmp = array();
            swap(tmp); 
        }
    }

    array(const std::initializer_list<int> &l) {
        n = l.size();
        data = new int[n];
        std::copy(l.begin(), l.end(), data);
        
    }
    
    void swap(array& obj) {
        std::swap(n, obj.n);
        std::swap(data, obj.data);
    }

    friend std::ostream& operator <<(
        std::ostream& os, const array& obj
    ) {
        for (size_t i = 0; i < obj.n; ++i)
            os << obj.data[i] << " ";
        return os;
    }
    
    int get(size_t i) {
        assert(data != nullptr);
        return data[i];
    }
};

#include <array>
#include <vector>

int main() {
    array a(5);
    std::array<int, 5> b;
    std::vector<int> c(5, 1);

    for (auto &&e : c) std::cout << e << " ";
    std::cout << "\n";
    c.push_back(2);
    for (auto &&e : c) std::cout << e << " ";
    
    return 0;
}