78 lines
2.1 KiB
OCaml
78 lines
2.1 KiB
OCaml
let year = 2023
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let day = 1
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module Part_1 = struct
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let run (input : string) : (string, string) result =
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let string_to_digits s =
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String.to_seq s |> Seq.map Char.escaped |> Seq.map int_of_string_opt
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|> Seq.flat_map Option.to_seq |> Seq.map Int.to_string |> List.of_seq
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in
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let rec concat_digits = function
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| [] -> 0
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| [ x ] -> int_of_string (x ^ x)
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| [ first; last ] -> int_of_string (first ^ last)
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| first :: _ :: xs -> concat_digits (first :: xs)
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in
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let result =
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String.split_on_char '\n' input
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|> List.map string_to_digits |> List.map concat_digits
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|> List.fold_left ( + ) 0 |> Int.to_string
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in
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Ok result
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end
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module Part_2 = struct
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let run (input : string) : (string, string) result =
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let word_to_digit_list =
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[
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("one", "1");
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("two", "2");
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("three", "3");
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("four", "4");
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("five", "5");
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("six", "6");
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("seven", "7");
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("eight", "8");
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("nine", "9");
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("1", "1");
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("2", "2");
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("3", "3");
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("4", "4");
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("5", "5");
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("6", "6");
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("7", "7");
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("8", "8");
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("9", "9");
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]
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in
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let rec find_first_digit string =
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match
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List.find_opt
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(fun (word, _) -> String.starts_with ~prefix:word string)
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word_to_digit_list
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with
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| Some (_, digit) -> digit
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| None ->
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find_first_digit (String.sub string 1 (String.length string - 1))
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in
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let rec find_last_digit string =
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match
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List.find_opt
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(fun (word, _) -> String.ends_with ~suffix:word string)
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word_to_digit_list
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with
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| Some (_, digit) -> digit
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| None -> find_last_digit (String.sub string 0 (String.length string - 1))
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in
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let concat_digits s =
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let first = find_first_digit s in
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let last = find_last_digit s in
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int_of_string (first ^ last)
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in
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let result =
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input |> String.split_on_char '\n'
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|> List.filter (fun s -> String.length s > 0)
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|> List.map concat_digits |> List.fold_left ( + ) 0 |> Int.to_string
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in
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Ok result
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end
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