main()
{
int N = 50;
int R = 5;
int *x, *z;
int n;
int i;
n = nCr(N, R);
printf("%dC%d = %d\n", N, R, n);
/*
n = nPr(N, R);
printf("%dP%d = %d\n", N, R, n);
*/
if ( (x = (int *)malloc( N * sizeof(int) )) == NULL ) {
printf("*** malloc failed for x\n");
exit(1);
}
for(i=0; i<N; i++) {
x[i] = i+1;
}
if ( (z = (int *)malloc( N * sizeof(int) )) == NULL ) {
printf("*** malloc failed for z\n");
exit(1);
}
combs(x, N, R, z, 0, comb_count, &n);
/* perms(x, N, R, z, 0, vec_print, NULL); */
}
/*---------------------------------------------------------------
Routine : combs
Purpose : Generate combinations, r objects from n.
(objects are integers in array a, length n)
f is called for each combination.
The arguments for f are as for vec_print above.
This routine is recursive.
---------------------------------------------------------------*/
void
combs(
int *a, /* IN - input array */
int n, /* IN - length of a */
int r, /* IN - length of combinations to take from a */
int *z, /* OUT - array to put combination into */
int zi, /* IN - index into z */
void f( int *, int, void * ), /* ? function to call for each comb generated */
void *p) /* ? user data for f() */
{
int i;
if ( r == 0 ) {
f(z, zi, p);
/* update progress bar (if required) */
current_progress += 1.0f;
while(current_progress > one_increment) {
GenerateNumericalProbabilityProgressBarInc();
current_progress -= one_increment;
}
return;
} else {
for(i = 0; i < n-r+1 && !GenerateNumericalProbabilityCheckForInterrupt(); i++) {
z[zi] = a[i];
combs(a+i+1, n-i-1, r-1, z, zi+1, f, p);
}
}
} /* combs */
int main(){
int n,k;
ll res;
while(1){
scanf("%d %d",&n,&k);
if(!n && !k) break;
res = combs(n,k);
printf("%lld\n",res);
}
return 0;
}
vector< vector<T> > combinations(vector<T> &v, unsigned int k) {
unsigned int next = 0;
if(k > v.size())
throw k_GreaterThan_n_Exception();
vector< vector<T> > combs( binomialCoefficient(v.size(), k) );
vector<bool> binary(v.size());
fill(binary.end() - k, binary.end(), true);
do {
for(unsigned int i = 0 ; i < v.size() ; i++) {
if(binary[i])
combs[next].insert(combs[next].end(), v[i]);
}
next++;
} while(next_permutation(binary.begin(), binary.end()));
return combs;
}
