-module(day1).
-export([main/0]).


main() ->
    {ok, Content} = file:read_file("input.txt"),
    Lines = string:split(string:trim(Content), "\n", all),
    {List1, List2} = lists:foldl(fun parse_line/2, {[], []}, Lines),
    SortedList1 = lists:sort(List1),
    SortedList2 = lists:sort(List2),
    Distance = calculate_distance(SortedList1, SortedList2),
    io:format("Result: ~p~n", [Distance]).


parse_line(Line, {Acc1, Acc2}) ->
    [Str1, Str2] = string:split(string:trim(Line), "   ", all),
    {Num1, _} = string:to_integer(Str1),
    {Num2, _} = string:to_integer(Str2),
    {[Num1 | Acc1], [Num2 | Acc2]}.


calculate_distance(List1, List2) ->
    lists:sum([abs(A - B) || {A, B} <- lists:zip(List1, List2)]).