#include <iostream>
#include <vector>
#include <cstring>
#include <memory>
#include <algorithm>


template <typename T>
class DiyVector
{
private:
    unsigned int elSize = 0;
    unsigned int totalSize = 10;
    T* elements = nullptr;

    void reserve(unsigned int size)
    {
        if (size < totalSize)
            return; //Don't shrink
        else
        {
            T* newData = new T[size];
            for (unsigned int i = 0; i < elSize; ++i)
                newData[i] = elements[i];
            elements = newData;
        }
    }

public:
    DiyVector() : totalSize(10), elSize(0), elements(new T[totalSize]){}
    ~DiyVector() { delete elements;  }

    T& at(unsigned int index) const
    {
        if (index >= elSize)
            throw new OutOfRange();
        return elements[index];
    }

    unsigned int size() const
    {
        return elSize;
    }

    void pushBack(const T& item)
    {
        if (elSize + 1 > totalSize)
            reserve(totalSize * 1.5);
        elements[elSize++] = item;
    }

    void popBack()
    {
        --elSize;
    }

    void erase(unsigned int index)
    {
        if (index >= elSize)
            throw new OutOfRange();
        for (unsigned int i = index; i < elSize - 1; ++i)
        {
            elements[i] = elements[i] + 1;
        }
    }

    void insert(unsigned int index, const T& item)
    {
        if (index >= elSize + 1)
            throw new OutOfRange();
        if (elSize + 1 > totalSize)
            reserve(totalSize * 1.5);
        elSize += 1;
        for (unsigned int i = index + 1; i < elSize - 1; ++i)
        {
            elements[i + 1] = elements[i];
        }
        elements[index] = item;
    }

    void print()
    {
        for (int i = 0; i < elSize; i++)
        {
            std::cout << elements[i] << " ";
        }
    }

    class OutOfRange {};
};


int main()
{
    DiyVector<int> v;
    std::cout << "array size: " << v.size() << "\n";
    v.pushBack(3);
    std::cout << "3\n";
    std::cout << "array size: " << v.size() << "\n";
    v.pushBack(4);
    std::cout << "4\n";
    v.pushBack(6);
    std::cout << "6\n";
    v.pushBack(2);
    std::cout << "2\n";
    std::cout << "array size: " << v.size() << "\n";
    v.print();
    std::cout << "\n";
    v.insert(1, 7);
    v.print();
    std::cout << "\n";
    v.erase(1);
    v.print();
    std::cout << "\n";
    v.pushBack(5);
    v.print();
    std::cout << "\n";
}