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29 lines
898 B
29 lines
898 B
-module(day4).
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-export([solve/1]).
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solve(InputData) ->
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Lines = binary:split(InputData, <<$\n>>, [trim_all, global]),
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solver(Lines, {0, 0}).
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solver([], Acc) -> Acc;
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solver([Entry | Rest], {Part1, Part2}) ->
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Ranges = binary:split(Entry, <<",">>, [trim_all, global]),
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[[F1, F2], [S1, S2]] = lists:map(fun(Range) -> binary:split(Range, <<"-">>, [trim_all, global]) end, Ranges),
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First = {binary_to_integer(F1), binary_to_integer(F2)},
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Second = {binary_to_integer(S1), binary_to_integer(S2)},
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Intersection = range_intersect(First, Second),
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{P1Flag, P2Flag} =
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case Intersection of
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First -> {1, 1};
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Second -> {1, 1};
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SomethingElse ->
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case range_is_empty(Intersection) of
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false -> {0, 1};
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true -> {0, 0}
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end
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end,
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solver(Rest, {Part1+P1Flag, Part2+P2Flag}).
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range_is_empty({Bottom, Top}) -> Top < Bottom.
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range_intersect({B1, T1}, {B2, T2}) -> {max(B1, B2), min(T1, T2)}.
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