How to invert order in QuickSort

[rafazz]

Hello! Iam trying to reverse my order of quicksort in C from asc order (1-99) that is the original way of the algoritm, to descending (99-1). I've tried so many ways that iam a kind of lost now!:s

The original quicksort is:

void swap(int* a, int* B) {
  int tmp;
  tmp = *a;
  *a = *b;
  *b = tmp;
}
 
int partition(int vec[], int left, int right) {
  int i, j;
 
  i = left;
  for (j = left + 1; j <= right; ++j) {
    if (vec[j] < vec[left]) {
      ++i;
      swap(&vec[i], &vec[j]);
    }
  }
  swap(&vec[left], &vec[i]);
 
  return i;
}
 
void quickSort(int vec[], int left, int right) {
  int r;
 
  if (right > left) {
    r = partition(vec, left, right);
    quickSort(vec, left, r - 1);
    quickSort(vec, r + 1, right);
  }
}

Thanks for all! Good work!

[Salem]

> if (vec[j] < vec[left])
What does this do?

More importantly, WHY is it < ?

When you know that, you should know the answer to your question.