49 lines
1.6 KiB
Prolog
49 lines
1.6 KiB
Prolog
:- table lookup_in/3.
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:- table lookup/3.
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answer(Answer) :-
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seeds(SeedsMap),
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seed_list(SeedsMap, Seeds),
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locations_of_seeds(Seeds, Locations),
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min(Locations, Answer).
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% seed_list(Pairs, FlattenedListOfSeeds) builds the seeds list from the pairs
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seed_list([], []).
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seed_list([Seed, 1 | RestOfPairs], [Seed | RestOfSeeds]) :-
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seed_list(RestOfPairs, RestOfSeeds).
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seed_list([Seed, Range | RestOfPairs], [Seed | RestOfSeeds]) :-
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Range > 1,
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NewSeedStart is Seed + 1,
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NewRange is Range - 1,
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seed_list([NewSeedStart, NewRange | RestOfPairs], RestOfSeeds).
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% locations_of_seeds(Seeds, Locations)
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locations_of_seeds([], []).
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locations_of_seeds([Seed | RestOfSeeds], [Location | RestOfLocations]) :-
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lookup_in(seed_to_soil, Seed, Soil),
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lookup_in(soil_to_fertilizer, Soil, Fertilizer),
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lookup_in(fertilizer_to_water, Fertilizer, Water),
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lookup_in(water_to_light, Water, Light),
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lookup_in(light_to_temperature, Light, Temperature),
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lookup_in(temperature_to_humidity, Temperature, Humidity),
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lookup_in(humidity_to_location, Humidity, Location),
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locations_of_seeds(RestOfSeeds, RestOfLocations).
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% lookup_in(NamedMap, In, Out)
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lookup_in(NamedMap, In, Out) :-
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G =.. [NamedMap, Map], G,
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lookup(Map, In, Out).
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% lookup(Map, In, Out)
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lookup([], In, In).
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lookup([[OutStart, InStart, Range] | RestOfMap], In, Out) :-
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((In >= InStart, In < InStart + Range) ->
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Out is OutStart + (In - InStart);
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lookup(RestOfMap, In, Out)).
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% min(List, Min) finds min value of a list
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min([X], X).
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min([Item | Rest], Min) :-
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min(Rest, MinRest),
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(Item < MinRest -> Min is Item; Min is MinRest).
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