Неверный вывод количества тактов

template<typename iterator>
std::pair<int, std::pair<iterator, iterator>> maxCrosssSubArray(iterator begin, iterator middle, iterator end)
{
    std::pair<int, std::pair<iterator, iterator>> left;
    left.first = 0;
    left.second.first = middle;
    left.second.second = middle;
    std::pair<int, std::pair<iterator, iterator>> right;
    right.first = 0;
    right.second.first = middle + 1;
    right.second.second = middle + 1;
    int left_sum = 0;
    int right_sum = 0;
    iterator i_left = middle;
    iterator i_right = middle + 1;
    while (i_left != begin - 1)
    {
        left_sum += *i_left;
        --i_left;
        if (left_sum > left.first)
        {
            left.first = left_sum;
            left.second.first = i_left;
        }
    }
    while (i_right != end)
    {
        right_sum += *i_right;
        ++i_right;
        if (right_sum > right.first)
        {
            right.first = right_sum;
            right.second.second = i_right;
        }
    }
    return std::make_pair(left.first + right.first, std::make_pair(left.second.first, right.second.second));
}
 
template<typename iterator>
std::pair<int, std::pair<iterator, iterator>> maxSubArray(iterator begin, iterator end)
{
    if (begin + 1 != end)
    {
        iterator middle = begin + (end - begin) / 2;
        auto left_sum = maxSubArray(begin, middle);
        auto right_sum = maxSubArray(middle, end);
        auto cross_sum = maxCrosssSubArray(begin, middle, end);
        auto max = std::max(cross_sum, std::max(left_sum, right_sum));
        return max;
    }
    else
    {
        return std::make_pair(*begin, std::make_pair(begin, end));
    }
}
 
template<typename iterator>
int _maxSubArray(iterator begin, iterator end)
{
    int max_sum = INT_MIN;
    for (iterator i = begin; i != end; ++i)
    {
        int temp_sum = 0;
        for (iterator j = i; j != end; ++j)
        {
            temp_sum += *j;
            if (temp_sum > max_sum)
            {
                max_sum = temp_sum;
            }
        }
    }
    return max_sum;
}
int main()
{
    std::vector<int> arr = { 13, -3, -25, 20, -3, -16, -23, 18, 20, -7, 12, -5, -22, 15, -4, 7 };
    clock_t t1 = clock();
    std::cout << "max = " << maxSubArray(arr.begin(), arr.end()).first << std::endl;
    clock_t t2 = clock();
    std::cout << "clock = " << (t2 - t1) << std::endl << std::endl;
    t1 = clock();
    std::cout << "max = " << _maxSubArray(arr.begin(), arr.end()) << std::endl;
    t2 = clock();
    std::cout << "clock = " << (t2 - t1) << std::endl;
    return 0;
}