#include <iostream>

using namespace std;

inline double area(double a, double h) {
    return (a * h) / 2;
}

unsigned int sum(unsigned int *arr, size_t size) {
    if (size > 0)
        return arr[size - 1] + sum(arr, size - 1);
    return 0;
}

unsigned int sum(unsigned int first, unsigned int step, unsigned int count) {
    if (count > 1) {
        return first + sum(first + step, step, count - 1);
    }
    return first;
}

float sum(float first, float step, unsigned int count) {
    if (count > 1) {
        return first + sum(first + step, step, count - 1);
    }
    return first;
}

double sum(double first, double step, unsigned int count) {
    if (count > 1) {
        return first + sum(first + step, step, count - 1);
    }
    return first;
}

template<class T, size_t SIZE = 0>
void maximum(T arr[SIZE]) {
    size_t maxi = 0;

    for (size_t i = 0; i < SIZE; ++i) {
        if (arr[i] > arr[maxi])
            maxi = i;
    }

    T t = arr[0];
    arr[0] = arr[maxi];
    arr[maxi] = t;
}

int main()
{
    unsigned int arr[] = { 1, 2, 3 };
    std::cout << area(10., 5.) << std::endl;
    std::cout << sum(arr, 3) << std::endl;
    std::cout << sum(5U, 1U, 5U) << std::endl;
    std::cout << sum(0.5f, 0.1f, 5) << std::endl;
    std::cout << sum(0.5, 0.1, 5) << std::endl;
    maximum<unsigned int, 3>(arr);
    std::cout << arr[0] << std::endl;
    return 0;
}