evenFibonacciNumbers.c

#include <stdio.h>
#include <string.h>

int main(int argc, char *argv[]) {
    (void) argc;
    (void) argv;

    //stores the last two terms, and the new sum
    int terms[] = {1, 2, 3};
    //stores indeces used to access the above array,
    // it cycles periodically, so one time I'm summing the last two which are the 0th and 1st into 2nd term, the new one
    //next time I sum the the last two, which now are the 2nd and the 0th into the new sum which is the 1st, so on and so forth...
    const char INDECES[3][3] = {
        {0, 1, 2},
        {1, 2, 0},
        {2, 0, 1}
    };
    const char *indeces = INDECES[2];
    int TERM_MAX = 4000000;
    long int sum = terms[1];

    do {
        if(!(terms[indeces[0]] & 1))
            sum += terms[indeces[0]];
 
        //cycle indices
        if(0 == indeces[0])
            indeces = INDECES[1];
        else if(1 == indeces[0])
            indeces = INDECES[2];
        else
            indeces = INDECES[0];

        terms[indeces[0]] = terms[indeces[1]] + terms[indeces[2]];

    } while(terms[indeces[0]] < TERM_MAX);

    fprintf(stderr, "%i", sum);

    return 0;
}

انا دماغى لفت من الحل ده ... feeling dizzy