Project Euler #2

prog2.cpp

// Answer: 4,613,732

unsigned int fib(unsigned int n) {
    return n <= 1 ? n : fib(n-1) + fib(n-2);
}

int main()
{
    unsigned int sum(0);

    for (unsigned int i(2), r(1); r <= 4000000; r = fib(++i))
        if (r % 2 == 0) sum += r;
}