1 parse_move(['L'|Rest], N) :-
2     number_chars(N0, Rest),
3     N is -N0.
4 
5 parse_move(['R'|Rest], N) :-
6     number_chars(N, Rest).
7 
8 parse_input(File, Moves) :-
9     read_file_to_string(File, Content, []),
10     split_string(Content, "\n", "", Lines0),
11     exclude(=(""), Lines0, Lines),
12     maplist(string_chars, Lines, CharLists),
13     maplist(parse_move, CharLists, Moves).
14 
15 passed_zero_left(0, _, Q, Count) :- Count is Q - 1.
16 passed_zero_left(_, 0, Q, Count) :- Count is Q + 1.
17 passed_zero_left(_, _, Q, Q).
18 
19 passed_count(Move, Pos, NewPos, Q, Count) :-
20     Move < 0,
21     passed_zero_left(Pos, NewPos, Q, Count).
22 
23 passed_count(_, _, _, Q, Q).
24 
25 move_dial(Pos, N, NewPos, Passed0Count) :-
26     T is Pos + N,
27     divmod(T, 100, Q0, NewPos),
28     Q is abs(Q0),
29     passed_count(N, Pos, NewPos, Q, Passed0Count).
30 
31 solve(_, [], 0, 0).
32 solve(Pos, [Move|Rest], Task1, Task2) :-
33     move_dial(Pos, Move, NewPos, T2R1),
34     ( NewPos =:= 0 -> T1R1 = 1 ; T1R1 = 0 ),
35     solve(NewPos, Rest, T1R2, T2R2),
36     Task1 is T1R1 + T1R2,
37     Task2 is T2R1 + T2R2.
38 
39 solve(Moves, Task1, Task2) :-
40     solve(50, Moves, Task1, Task2).
41 
42 :-
43     parse_input("input/01.txt", Moves),
44     solve(Moves, Task1, Task2),
45     format("~d ~d~n", [Task1, Task2]).