euler2

Problem

Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be: 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ... By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.

#include <stdio.h>

#define NUM    4000000
int main(int argc, const char *argv[])
{
    int fibonacci, prev, pprev;
    int sum;

    pprev = 1, prev = 2, fibonacci = 0;
    sum = 2;
    while (fibonacci< NUM) {
        if (!(fibonacci % 2)) {
            sum += fibonacci;
        }
        fibonacci = prev + pprev;
        pprev = prev;
        prev = fibonacci;
        printf("fibonacci: %d\n", fibonacci);
    }

    printf("sum = %d\n", sum);

    return 0;
}