quicksort.c - Funktionen do_partitioning der opdeler tabellens elementer op i store og små.

Lektion 8 - slide 26 : 27 Program 1

/* Do a partitioning of a, and return the partitioning
   points in *point_left and *point_right */
void do_partitioning(element a[], index from, index to,
                     index *point_left, index *point_right){
 index i,j;
 element partitioning_el;

 i = from - 1; j = to + 1;
 partitioning_el = a[from];
 do{
   do {i++;} while (a[i] < partitioning_el);  
   do {j--;} while (a[j] > partitioning_el);  
   if (i < j) swap(&a[i],&a[j]);
 } while (i < j); 

 if (i > j) {
   *point_left = j; *point_right = i;}
 else {
   *point_left = j-1; *point_right = i+1;}  
}