let print_tab tab =
    for i = 0 to (Array.length tab) - 1 do
        print_int i;
        print_string " : ";
        print_int tab.(i);
        print_string "\t"
    done
in
let merge_sorting lt rt =
    let ll = Array.length lt in
    let lr = Array.length rt in
    let l = ll + lr in
    let ret = Array.make (l) 0 in
    let li = ref 0 in
    let ri = ref 0 in
    while (!li < ll && !ri < lr) do
        if (rt.(!ri) < lt.(!li)) then
        (
            ret.(!li + !ri) <- rt.(!ri);
            ri := !ri + 1
        )
        else
        (
            ret.(!li + !ri) <- lt.(!li);
            li := !li + 1
        )
    done;
    while (!li < ll) do
        ret.(!li + !ri) <- lt.(!li);
        li := !li + 1
    done;
    while (!ri < lr) do
        ret.(!ri + !li) <- rt.(!ri);
        ri := !ri + 1
    done;
    ret
in
let rec merge_sort tab =
    let l = Array.length tab in
    if (l < 2) then tab else
    (
        let hl = Array.sub tab 0 (l / 2) in
        let hr = Array.sub tab (l/2) (l - l/2) in
        let sl = merge_sort hl in
        let sr = merge_sort hr in
        merge_sorting sl sr
    )
in
print_tab (merge_sort [|2;3;6;4;1;79;4|]);;