let indice_max (t : 'a array) : int =
  let n = Array.length t in
    if n  = 0
      then failwith "Tableau vide"
      else
        let max = ref t.(0) and indice = ref 0 in
          for i = 1 to n - 1 do
            if t.(i) > !max then
              begin 
                max := t.(i) ;
                indice := i ;
              end ;
          done ;
          !indice ;;


let extrait (t : 'a array) (k : int) : ('a array) =
  let n = Array.length t in
  let ans = Array.make (n - 1) t.(0) in  (* Tableau supposé non vide...*)
  for i = 0 to (n - 1) do
    if i < k then
               ans.(i) <- t.(i)
             else
               if i > k then ans.(i - 1) <- t.(i)
  done ;
  ans ;;


let rec tri_selection (t : 'a array) =
  let n = Array.length t in
  if n > 1 then
      begin
        let i = indice_max t in
        let max = t.(i) in
        let u = extrait t i in
        tri_selection u;
        for j = 0 to n - 2 do
          t.(j) <- u.(j)
        done ;
        t.(n - 1) <- max ;
      end ;;

let test =  [|-3; 5; -8; 7; 0; 1; -6; 50; -10|];;
tri_selection test ;;
test;;

let test =  [|-3; 5|];;
tri_selection test ;;
test;;

let test =  [|3; -5|];;
tri_selection test ;;
test;;

let test =  [|3|];;
tri_selection test ;;
test;;

let test =  [||];;
tri_selection test ;;
test;;