Probability

#include <stdio.h>

unsigned char x[16] = { 1, 1, 1, 1, 1, 1,
            2, 2, 2, 2, 2,
            3, 3, 3, 3, 3};

unsigned int sum = 0;
unsigned int a = 0, b = 0;

void rec(unsigned int i, unsigned int count) {
    if (count == 3) {
        if (sum == 6) a++;
        b++;
        return;
    }
    for (; i < 16; i++) {
        sum += x[i];
        rec(i+1, count+1);
        sum -= x[i];
    }
}

int main() {
    rec(0, 0);
    printf("%d/%d=%f\n", a, b, (float) a/b);
    return 0;
}