alan day8 erlang

2021-12-08 20:27:36 +00:00
parent e3eab87b08
commit 433614ef09
2 changed files with 316 additions and 0 deletions
--- a/day8/day8.erl
+++ b/day8/day8.erl
@@ -0,0 +1,116 @@
+%% to compile: erlc day8.erl
+%% to run: erl -noshell -s day5 solve
+%%
+-module(day8).
+
+-export ([solve/0, solve/1, solve/2]).
+-export ([read_input/0]).
+
+solve() ->
+    solve(['1']),
+    solve(['2']),
+    init:stop().
+
+solve(A) ->
+    solve(A, read_input()).
+
+solve(['1'], D) ->
+    io:format("The solution to ~p puzzle1 is: ~p~n", [?MODULE, solve(1, D)]);
+solve(1, D) ->
+    solution1(D);
+solve(['2'], D) ->
+    io:format("The solution to ~p puzzle2 is: ~p~n", [?MODULE, solve(2, D)]);
+solve(2, D) ->
+    solution2(D).
+
+read_input() ->
+    {ok, IO} = file:open("input.txt", 'read'),
+    Data = read_input(IO),
+    file:close(IO),
+    Data.
+
+read_input(IO) ->
+	read_input(IO, []).
+
+read_input(IO, Input) ->
+    case read_line(IO) of
+	'eof' ->Input;
+	Line -> read_input(IO, lists:reverse([Line|Input]))
+    end.
+
+read_line(IO) ->
+	case file:read_line(IO) of
+		'eof' -> 'eof';
+		{ok, Line} -> parse_line(Line)
+	end.
+
+parse_line(Line) ->
+    [string:tokens(X, " \n") || X <- string:split(Line, "|")].
+
+solution1(Input) ->
+   lists:foldl(fun([_,X], Acc) -> count_unique(X, Acc) end, 0, Input).
+
+solution2([]) -> 0;
+solution2([[I|[O]]|T]) ->
+   [One] = find_length(2,I),
+   [Seven] = find_length(3,I),
+   [Four] = find_length(4,I),
+   [Eight] = find_length(7,I),
+   Three = find_three(find_length(5, I), One),
+   Nine = find_nine(find_length(6, I), Four),
+   [Five, Two] = find_five_and_two(find_length(5, I), Three, Four),
+   [Six, Zero] = find_six_and_zero(find_length(6, I), Nine, One),
+   Key = [{lists:sort(One), 1},{lists:sort(Two), 2},{lists:sort(Three), 3},{lists:sort(Four), 4},{lists:sort(Five), 5},{lists:sort(Six), 6},{lists:sort(Seven), 7},{lists:sort(Eight), 8},{lists:sort(Nine), 9}, {lists:sort(Zero), 0}],
+   [{_, A},{_,B},{_,C},{_,D}] = [lists:keyfind(lists:sort(X), 1, Key) || X <- O],
+   (A * 1000 + B * 100 + C * 10 + D)  + solution2(T).
+
+count_unique([], V) -> V;
+count_unique([H|T], V) ->
+   count_unique(T, V + count(length(H))).
+
+count(2) -> 1;
+count(4) -> 1;
+count(3) -> 1;
+count(7) -> 1;
+count(_) -> 0.
+
+find_length(_Len, []) -> [];
+find_length(Len, [H|T]) when  length(H) == Len -> [H|find_length(Len, T)];
+find_length(Len, [_H|T]) -> find_length(Len, T).
+
+find_three([H|T], One) ->
+   case length(minus(H, One)) of 
+	   3 -> H;
+	   _ -> find_three(T, One)
+   end.
+
+find_nine([H|T], Four) ->
+   case length(minus(H, Four)) of 
+	   2 -> H;
+	   _ -> find_nine(T, Four)
+   end.
+
+find_five_and_two(Fives, Three, Four) ->
+	N = lists:delete(Three, Fives),
+	find_five_and_two(N, Four).
+
+find_five_and_two([H,T], Four) ->
+   case length(minus(H, Four)) of
+           3 -> [T, H];
+           2 -> [H, T]
+   end.
+find_six_and_zero(Sixes, Nine, One) ->
+        N = lists:delete(Nine, Sixes),
+        find_six_and_zero(N, One).
+
+find_six_and_zero([H,T], One) ->
+   case length(minus(H, One)) of
+           4 -> [T, H];
+           5 -> [H, T]
+   end.
+
+minus(X, Y) ->
+    lists:foldl(fun(T, Acc) -> lists:delete(T, Acc) end, X, Y).
+
+plus(X, Y) ->
+    lists:usort(X ++ Y).