int arr[5] = {2, 4, 6, 8, 10};
int sum = 0;
for (int i = 0; i < 5; i++) {
    switch (arr[i] % (1|2)) {
        case 0: sum += 1; break;
        case 1: sum += 2; break;
        case 2: sum += 3; break;
    }
}