int main(){
int arr[20], arraysize, sub, i;
printf("Enter the size of array\n");
scanf("%d", &arraysize);
printf("Enter the element of the array\n");
for(i = 0; i < arraysize; i++){
scanf("%d", &arr[i]);
}
printf("\n\n");
printsubset(arr, arraysize);
return 0;
}
/*
a : pointer to an array of frequency_t elements.
N : size of the above array.
sum : sum we are looking for.
result : array where selected numbers will be stored.
index : caller must initially setup result and index.
*/
void subsetsum(frequency_t* a, int N, int sum, int* result, int index)
{
if(N == 0) return;
int psum = sum - a[0].item;
//we cannot use an element if its frequency count is <= zero.
if(a[0].count <= 0) goto try_with_next_element;
result[index] = a[0].item;
//if psum is zero, we found a combination which adds up to sum, so print it. otherwise decrease the frequency
//count of the current element and make a recursive call.
if(psum == 0)
printsubset(result, index + 1);
else
{
--a[0].count;
subsetsum(a, N, psum, result, index + 1);
++a[0].count;
}
try_with_next_element:
subsetsum(a + 1, N - 1, sum, result, index);
}
