/* combinations.h  generate all combinations of n things taken m at a time */

int combinations(int n, int m, int vn[], int vm[], int *first);

/* return is 0 if more combinations to come. 1 if this is last             */
/* n is for n things     n! / ((n-m)! m!) combinations                     */
/* m is for m at a time                                                    */
/* vn must be the n items, unchanged by comb (can by pointers or indices)  */
/* vm must be of size m items, the returned combination each call          */
/* first must be 1 the first call, then set to internally                  */