let INFINI = 66666666;;
let mQuad = ref (INFINI, INFINI, INFINI, INFINI);;
let pBorne = ref 0;;

let addt x y = x + y;;
let mult x y = x * y;;
let sous x y = x - y;;
let div  x y = if y = 0 then 0 else x / y;;

let operateurs = make_vect 4 addt;;
operateurs.(0) <- addt;;
operateurs.(1) <- mult;;
operateurs.(2) <- sous;;
operateurs.(3) <- div;;

let borne a b c d =

    let plage = make_vect 3025 0 in


    (*****)

    let permutations l =

        let rec permut fixe = fun
            | [] [] -> [fixe]
            | debut [] -> []
            | debut (x::suite) -> (permut (fixe @ [x]) [] (debut @ suite)) @ (permut fixe (debut @ [x]) suite)
        in

        permut [] [] l
    in

    let perm = vect_of_list (permutations [a;b;c;d]) in

    for cur_perm = 0 to (vect_length perm - 1) do
        for op1 = 0 to 3 do
            for op2 = 0 to 3 do
                for op3 = 0 to 3 do
                    let p3 = operateurs.(op3) in
                    let p2 = operateurs.(op2) in
                    let p1 = operateurs.(op1) in

                    let a = hd (perm.(cur_perm)) in
                    let b = hd ( tl (perm.(cur_perm)) ) in
                    let c = hd ( tl (tl (perm.(cur_perm))) ) in
                    let d = hd ( tl (tl (tl (perm.(cur_perm)))) ) in

                    if (p3 (p2 (p1 a b) (c)) (d)) >= 0 then
                        plage.( p3 (p2 (p1 a b) (c)) (d) ) <- succ (plage.( p3 (p2 (p1 a b) (c)) (d) ));

                    if (p2 (p1 (a) (b)) (p3 (c) (d))) >= 0 then
                        plage.( p2 (p1 (a) (b)) (p3 (c) (d)) ) <- succ (plage.( p2 (p1 (a) (b)) (p3 (c) (d)) ));

                    if (p1 (a) (p2 (b) (p3 c d))) >= 0 then
                        plage.( p1 (a) (p2 (b) (p3 c d)) ) <- succ (plage.( p1 (a) (p2 (b) (p3 c d)) ));

                    if (p3 (p1 (a) (p2 b c)) (d)) >= 0 then
                        plage.( p3 (p1 (a) (p2 b c)) (d) ) <- succ (plage.( p3 (p1 (a) (p2 b c)) (d) ));

                    if (p1 (a) (p3 (p2 b c) (d))) >= 0 then
                        plage.( p1 (a) (p3 (p2 b c) (d)) ) <- succ (plage.( p1 (a) (p3 (p2 b c) (d)) ));
                done
            done
        done
    done;

    (*****)




    let indice = ref 1 in
    while plage.(!indice) > 0 do
        incr indice
    done;

    (!indice - 1)
;;

for a = 1 to 9 do
    for b = a+1 to 9 do
        for c = b+1 to 9 do
            for d = c+1 to 9 do
                let boborne = borne a b c d in
                if (!pBorne) < boborne
                then
                    begin
                    pBorne := boborne;
                    mQuad := (a,b,c,d)
                    end
            done
        done
    done
done;;

mQuad;;