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  1. #include <stdio.h>
  2.  
  3. int count_combinations(
  4.     int itemCosts[]
  5. ,   size_t costCount
  6. ,   int pickedItems[]
  7. ,   size_t pickedCount
  8. ,   size_t pickedTargetCount
  9. ,   size_t minIndex
  10. ,   int funds
  11. ) {
  12.     if (pickedCount == pickedTargetCount) {
  13.         // This is the base case. It has the code similar to
  14.         // the "if" statement from your code, but the number of items
  15.         // is not fixed.
  16.         int sum = 0;
  17.         for (size_t i = 0 ; i != pickedCount ; i++) {
  18.             sum += pickedItems[i];
  19.         }
  20.         if (sum <= funds) {
  21.         	for (size_t i = 0 ; i != pickedCount ; i++) {
  22.                 printf("%d ", pickedItems[i]);
  23.             }
  24.             printf("\n");
  25.         }
  26.         // The following line will return 0 or 1,
  27.         // depending on the result of the comparison.
  28.         return sum <= funds;
  29.     } else {
  30.         // This is the recursive case. It is similar to one of your "for"
  31.         // loops, but instead of setting "one", "two", or "three"
  32.         // it sets pickedItems[0], pickedItems[1], etc.
  33.         int res = 0;
  34.         for (size_t i = minIndex ; i != costCount ; i++) {
  35.             pickedItems[pickedCount] = itemCosts[i];
  36.             res += count_combinations(
  37.                 itemCosts
  38.             ,   costCount
  39.             ,   pickedItems
  40.             ,   pickedCount+1
  41.             ,   pickedTargetCount
  42.             ,   i+1
  43.             ,   funds
  44.             );
  45.         }
  46.         return res;
  47.     }
  48. }
  49.  
  50.  
  51. int main(void) {
  52. 	int itemCosts[] = {1, 3, 5, 7}; // The costs
  53.     int pickedItems[2]; // No need to initialize this array
  54.     int res = count_combinations(itemCosts, 4, pickedItems, 0, 2, 0, 8);
  55.     printf("Got %d combinations\n", res);
  56. 	return 0;
  57. }
  58.  
Success #stdin #stdout 0s 2112KB
comments (?)
stdin
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Standard input is empty
stdout
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1 3 
1 5 
1 7 
3 5 
Got 4 combinations
https://ideone.com/oiaPX2
language:
C99 (gcc 8.3)
created:
8 years ago
visibility:
public

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