Letterpress solver

letterpress.ml

(* ocamlbuild letterpress.native *)
 
let rec mkword ?(i=0) ?(l=[]) w =
  if i = (String.length w) then
    let l' = List.map Char.lowercase l in
    List.fast_sort Char.compare l'
  else
    mkword ~i:(i+1) ~l:(w.[i]::l) w

let rec contains b w = match (b,w) with
  | (x::b', y::_) when x < y -> contains b' w
  | (x::b', y::w') when x = y -> contains b' w'
  | (_, []) -> true
  | _ -> false

let () =
  let board = Sys.argv.(1) in

  let b = mkword board in

  try
    while true do
      let word = input_line stdin in
      let w = mkword word in
      if contains b w then
        Printf.printf "%s\n" word
      else ()
    done
  with
    End_of_file -> ()

% time ruby /tmp/slowword.rb  > /tmp/slow
        6.29 real         6.25 user         0.00 sys
% time letterpress.native asviqaazotvepjffysjrrasdl < /usr/share/dict/words > /tmp/fast
        0.26 real         0.24 user         0.00 sys