void partition(int *a, int size) {
int pivot = a[0];
int left = 0, right = 0;
for(left = 1, right = size-1; left <= right; left++, right--) {
if(a[lef
You more or less answered your own question. You probably want to do something like this:
void partition(int *a, int size) {
int pivot = a[0];
int left, right;
for(left = 1, right = size-1; left < right; )
{
if(a[left] > pivot && a[right] <= pivot)
{
swap(left, right, a);
}
if(a[left] <= pivot) left++;
if(a[right] > pivot) right--;
}
}