#include <iostream>
#include <vector>

template <typename T> class DiyVector
{
    private:
        int elSize;
        int totalSize;
        T* elements;
    public:
        DiyVector()
        {
            elSize = 0;
            totalSize = 0;
            elements = new T [totalSize];
        }
        ~DiyVector()
        {
            delete[] elements;
        }

        T& at(unsigned int index) const
        {
            if (index > elSize - 1 || index < 0)
            {
                throw std::runtime_error ("OutOfRange");
            }
            else
            {
                return elements[index];
            }
        };

        unsigned int size() const
        {
            return elSize;
        }

        void pushBack(const T& item)
        {
            if (elSize < totalSize)
            {
                elements[elSize - 1] = item;
                elSize++;
            }
            else
            {
                totalSize++;
                T* temp = new T[totalSize];
                for(int i = 0; i < totalSize; i++)
                {
                    temp[i] = elements[i];
                }

                delete[] elements;
                elements = temp;
                pushBack(item);
            }
        }
        // append item at the end of vector

        void popBack()
        {
            elSize--;
        }
        // remove item at the end of vector
        // throws OutOfRan

        void erase(unsigned int index)
        {
            if(index > elSize - 1|| index < 0)
            {
                throw std::runtime_error ("OutOfRange");
            }

            if(index == elSize)
            {
                popBack();
            }
            else
            {
                for (int i = index; i < elSize - 1; i++)
                {
                    elements[i] = elements[i + 1];
                }
                erase(index);
            }
        }
        // remove element at index
        // throws OutOfRange

        void print()
        {
            for(int i = 0; i < elSize - 1; i++)
            {
                std::cout << elements[i] << " ";
            }
        }

        void insert(unsigned int index, const T& item)
        {
            if(elSize < totalSize)
            {
                for (int i = index; i < elSize - 1; i++)
                {
                    elements[i + 1] = elements[i];
                }
                elements[index] = item;
                elSize++;
            }
            else
            {
                totalSize++;
                T* temp = new T[totalSize];
                for(int i = 0; i < totalSize - 1; i++)
                {
                    temp[i] = elements[i];
                }
                delete[] elements;
                elements = temp;
                insert(index, item);
            }
        }
        // insert item before element at index, with:
        // 0 <= index <= size()
        // throws OutOfRange

        class OutOfRange
        {};
};