f.ml

let update (x, y) (i, j) =
    if !y - !x < !j - !i then
    (
        y := !j;
        x := !i;
    );

let triangle arr =
    if Array.length arr < 3 then arr else
    let arr = Array.copy arr in
    let i = ref 0 in
    let j = ref 2 in
    let best = (ref 0, ref 2) in
    let (i, j) = 
    begin
        while !j < Array.length arr do
            (
                (
                if arr.(!i) + arr.(!i+1) > arr.(!j) then
                    j := !j + 1
                else
                    i := !i + 1
                );
                update best (i, j)
            );
        done;
        best
    end
    in (i, j)