fun iterate([],i,listy,visited,wyn) =
let
  val k1 = if Array.sub(visited,i) = 0 then
    Array.update(wyn,0,i::Array.sub(wyn,0)) else ()
  val k2 = Array.update(visited,i,1)
in
  wyn
end
  |
  iterate(top::l,i,listy,visited,wyn) = let
    val k1 = if Array.sub(visited,i) = 0 then
      Array.update(wyn,0,i::Array.sub(wyn,0)) else ()
    val k2 = Array.update(visited,i,1)
    val k = if Array.sub(visited,top) = 0 then iterate(Array.sub(listy,top),top,listy,visited,wyn) else
      wyn
                                      in
                                        iterate(l,i,listy,visited,wyn)
                                      end;

fun iterate2(i,listy,visited,wyn) =
  if i = Array.length(listy) then wyn
  else let
    val k1 = iterate(Array.sub(listy,i),i,listy,visited,wyn)
       in
    iterate2(i+1,listy,visited,wyn)
       end;

fun dfs l = let
  val listy = Array.fromList l
  val visited = Array.array (length l,0)
  val wyn = Array.array(1,[])
in
  rev (Array.sub(iterate2(0,listy,visited,wyn),0))
(*rev (Array.sub(iterate(Array.sub(listy,0),0,listy,visited,wyn),0)) *)
end;