QuickSort

int partition( int a[], int l, int r) {
   int pivot, i, j, t;
   pivot = a[l];
   i = l; j = r+1;

   while(1){
   	do ++i; while( a[i] <= pivot && i <= r );
   	do --j; while( a[j] > pivot );
   	if( i >= j ) break;
   	t = a[i]; a[i] = a[j]; a[j] = t;
   }
   t = a[l]; a[l] = a[j]; a[j] = t;
   return j;
}

void quickSort(int a[], int l, int r) {
   int j;

   if( l < r ){
        j = partition( a, l, r);
       quickSort( a, l, j-1);
       quickSort( a, j+1, r);
   }
}