Day 4-1

day4.erl

@@ -0,0 +1,24 @@
+-module(day4).
+
+-export([solve/1]).
+
+solve(InputData) ->
+	Lines = binary:split(InputData, <<$\n>>, [trim_all, global]),
+	{part1(Lines), none}.
+
+part1([]) -> 0;
+part1([Entry | Rest]) ->
+	Ranges = binary:split(Entry, <<",">>, [trim_all, global]),
+	[[F1, F2], [S1, S2]] = lists:map(fun(Range) -> binary:split(Range, <<"-">>, [trim_all, global]) end, Ranges),
+	First = {binary_to_integer(F1), binary_to_integer(F2)},
+	Second = {binary_to_integer(S1), binary_to_integer(S2)},
+	io:format("~n~p ~p", [First, Second]),
+	case range_intersect(First, Second) of
+		First -> 1;
+		Second -> 1;
+		_SomethingElse -> io:format(" out"), 0
+	end + part1(Rest).
+
+range_empty() -> {0, -1}.
+range_is_empty({Bottom, Top}) -> Top < Bottom.
+range_intersect({B1, T1}, {B2, T2}) -> {max(B1, B2), min(T1, T2)}.