Hacker Rank Maximize XOR Erlang

maximize_xor.erl

-module(maximize_xor).
-export([main/0, test/0]).
-import(lists, [map/2, seq/2]).

main() ->
  I = {inputs, [2,4]},
  {inputs, [START|[STOP|_]]} = I,
  EXPANDED_GROUP = lists:seq(START,STOP),
  GROUPS = organize(EXPANDED_GROUP),
  MAX = maximize_bxor(GROUPS, 0),
  log(MAX).

organize(COUNTS) ->
  process(COUNTS, []).

log(MSG) -> io:format("~w~n",[MSG]).

%For HackerRank
inputs() ->
  {ok, [L, R]} = io:fread("", "~d~d"),
  {inputs, [L, R]}.

process([H|T], THUSFAR) ->
  THUSFAR1 = THUSFAR ++ lists:map(
    fun(X)-> {group,[H,X]} end, [H]++T
  ),
  process(T,THUSFAR1);
process([], THUSFAR) -> THUSFAR.

maximize_bxor([H|T], MAX) ->
  {group,[A,B]} = H,
  MAX1 = A bxor B,
  if
    MAX1 > MAX ->
        MAX2 = MAX1;
    true ->
        MAX2 = MAX
  end,
  maximize_bxor(T, MAX2);
maximize_bxor([], MAX) -> MAX.

test() ->
  [
    {group, {result, group_test()} },
    {maximize_2_4, {result, maximize_xor_test1()} },
    {maximize_1_10, {result, maximize_xor_test2()} }
  ].

group_test() ->
  Y = [2,3,4],
  [{group,[2,2]},{group,[2,3]},{group,[2,4]},{group,[3,3]},{group,[3,4]},{group,[4,4]}] = organize(Y),
  success.

maximize_xor_test1() ->
  GROUPS = [{group,[2,2]},{group,[2,3]},{group,[2,4]},{group,[3,3]},{group,[3,4]},{group,[4,4]}],
  7 = maximize_bxor(GROUPS, 0),
  success.

maximize_xor_test2() ->
  GROUPS = [
    {group,[1,1]},{group,[1,2]},{group,[1,3]},{group,[1,4]},{group,[1,5]},{group,[1,6]},{group,[1,7]},{group,[1,8]},{group,[1,9]},{group,[1,10]},
    {group,[2,2]},{group,[2,3]},{group,[2,4]},{group,[2,5]},{group,[2,6]},{group,[2,7]},{group,[2,8]},{group,[2,9]},{group,[2,10]},
    {group,[3,3]},{group,[3,4]},{group,[3,5]},{group,[3,6]},{group,[3,7]},{group,[3,8]},{group,[3,9]},{group,[3,10]},
    {group,[4,4]},{group,[4,5]},{group,[4,6]},{group,[4,7]},{group,[4,8]},{group,[4,9]},{group,[4,10]},
    {group,[5,5]},{group,[5,6]},{group,[5,7]},{group,[5,8]},{group,[5,9]},{group,[5,10]},
    {group,[6,6]},{group,[6,7]},{group,[6,8]},{group,[6,9]},{group,[6,10]},
    {group,[7,7]},{group,[7,8]},{group,[7,9]},{group,[7,10]},
    {group,[8,8]},{group,[8,9]},{group,[8,10]},
    {group,[9,9]},{group,[9,10]},
    {group,[10,10]}
  ],
  15 = maximize_bxor(GROUPS, 0),
  success.