37 lines
955 B
OCaml
37 lines
955 B
OCaml
module IntSet = Set.Make(Int)
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let read_ints =
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Bracket.infile_lines ~line:int_of_string ~of_seq:IntSet.of_seq
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let find_with target ints =
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let open IntSet in
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let p x = mem (target - x) ints in
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let res = min_elt (filter p ints) in
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res, target - res
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let find = find_with 2020
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let main_part_1 input =
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let ints = read_ints input in
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let x, y = find ints in
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Printf.printf "%d * %d = %d\n" x y (x * y)
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let main_part_2 input =
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let ints = read_ints input in
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let exception Found of int * int * int in
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let go x =
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match find_with (2020 - x) ints with
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| exception Not_found -> ()
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| y, z -> raise (Found (x, y, z))
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in
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match IntSet.iter go ints with
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| exception Found (x, y, z) ->
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Printf.printf "%d * %d * %d = %d\n" x y z (x * y * z)
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| _ -> raise Not_found
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let mains = [|main_part_1; main_part_2|]
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let main = function
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| [part; input] -> mains.(int_of_string part - 1) input
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| _ -> Usage.exit "1 <part> <infile>"
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