RosettaCodeData/Task/Semordnilap/Erlang/semordnilap.erl
Ingy döt Net 6f050a029e update
2013-06-05 21:47:54 +00:00

35 lines
1.1 KiB
Erlang

#!/usr/bin/env escript
main([]) -> main(["unixdict.txt"]);
main([DictFile]) ->
Dict = sets:from_list(read_lines(DictFile)),
Semordnilaps =
lists:filter(fun([W,R]) -> W < R end,
lists:map(fun(W) -> [W, lists:reverse(W)] end,
semordnilaps(Dict))),
io:fwrite("There are ~b semordnilaps in ~s~n",
[length(Semordnilaps), DictFile]),
lists:map(fun([W,R]) -> io:fwrite("~s/~s~n", [W, R]) end,
lists:sort(lists:sublist(shuffle(Semordnilaps),1,5))).
read_lines(Filename) when is_list(Filename) ->
{ ok, File } = file:open(Filename, [read]),
read_lines(File);
read_lines(File) when is_pid(File) ->
case file:read_line(File) of
{ok, Data} -> [chop(Data) | read_lines(File)];
eof -> []
end.
is_semordnilap(Word, Dict) ->
Rev = lists:reverse(Word),
sets:is_element(Word, Dict) and sets:is_element(Rev, Dict).
semordnilaps(Dict) ->
lists:filter(fun(W) -> is_semordnilap(W, Dict) end, sets:to_list(Dict)).
shuffle(List) ->
[X||{_,X} <- lists:sort([ {random:uniform(), N} || N <- List])].
chop(L) -> [_|T] = lists:reverse(L), lists:reverse(T).