Fibonacci implementations

fib.cpp

// C++ 11

#include <iostream>
#include <utility>
#include <string>


long long BinaryFib(long k)
{
    if (k == 0 || k == 1) return k;
    return BinaryFib(k-1) + BinaryFib(k-2);
}

std::pair<long, long> LinearFib(long k)
{
    if (k == 1) return std::make_pair(k, 0);
    
    auto p = LinearFib(k - 1);
    return std::make_pair(p.first + p.second, p.first);
}

int main(int argc, char**argv)
{
    if (argc != 3)
    {
        std::cout << "Usage:  fib [b|l] n" << std::endl;
        return -1;
    }
    
    long num = std::stol(argv[2]);
    
    std::cout << "Calculating the fib of " << num << std::endl;
    
    if (*argv[1] == 'b')
    {
        std::cout << "Binary Fib " << num << " = " << BinaryFib(num) << std::endl;
    } else
    if (*argv[1] == 'l')
    {
        auto k = LinearFib(num);
        std::cout << "Linear Fib " << num << " = " << k.second << std::endl;
    }
    
        
}