Daily #183 - Easy

easy.erl

%#!/usr/bin/env escript
-mode(compile).

read_stdin() -> 
    case io:get_line("") of
        eof ->
            io:format("Error: Recieved eof, expected line~n");
        Res ->
            read_stdin(list_to_integer(string:strip(Res, right, $\n)), [])
    end.
read_stdin(0, Acc) ->
    lists:reverse(Acc);
read_stdin(N, Acc) ->
    case io:get_line("") of
        eof ->
            io:format("Error: Expected ~p more lines~n", [N]);
        Res ->
            read_stdin(N-1, [string:strip(Res, right, $\n) | Acc])
    end.

sort_versions(A, B) ->
    Maj_A = list_to_integer(lists:nth(1, A)),
    Maj_B = list_to_integer(lists:nth(1, B)),
    case Maj_A =:= Maj_B of
        true  ->
            Min_A = list_to_integer(lists:nth(2, A)),
            Min_B = list_to_integer(lists:nth(2, B)),
            case Min_A =:= Min_B of
                true ->
                    compare_rest(lists:nth(3, A), lists:nth(3, B));
                false ->
                    Min_A < Min_B
            end;
        false ->
            Maj_A < Maj_B
    end.

compare_rest(A, B) ->
    {Patch_A, Patch_B} = get_patch(A, B),
    case Patch_A =:= Patch_B of
        true ->
            length(string:tokens(A, "-")) =/= 1;
        false ->
            Patch_A < Patch_B
    end.

get_patch(A, B) ->
    {list_to_integer(lists:nth(1, string:tokens(A, "-+"))),
     list_to_integer(lists:nth(1, string:tokens(B, "-+")))}.

main(_) ->
    Input = read_stdin(),
    Split = lists:map(fun(X) -> string:tokens(X, ".") end, Input),
    io:format("~p~n", [lists:sort(fun sort_versions/2, Split)]).