(* Baseline: quicksort over a list, returns sum of sorted result *)
let rec quicksort lst =
  match lst with
  | [] -> []
  | pivot :: rest ->
    let smaller = List.filter (fun x -> x < pivot) rest in
    let larger = List.filter (fun x -> x >= pivot) rest in
    List.append (quicksort smaller) (pivot :: quicksort larger) ;;
let sorted = quicksort [3; 1; 4; 1; 5; 9; 2; 6; 5; 3; 5] ;;
List.fold_left (fun a b -> a + b) 0 sorted