54 lines
1.6 KiB
OCaml
54 lines
1.6 KiB
OCaml
open Scanf
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let read_lines name =
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let ic = open_in name in
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let try_read () =
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try Some (input_line ic) with End_of_file -> None in
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let rec loop acc = match try_read () with
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| Some s -> loop (s :: acc)
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| None -> close_in ic; List.rev acc in
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loop []
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let handle_line line =
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sscanf line "%d %d" (fun num1 num2 -> (num1, num2))
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let sort_list l =
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List.sort compare l
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let build_lists lines =
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let rec loop lines l1 l2 = match lines with
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| [] -> (l1, l2)
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| head :: tail ->
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let (num1, num2) = handle_line head in
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loop tail (l1 @ [num1]) (l2 @ [num2]) in
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loop lines [] [] |> (fun (l1, l2) -> (sort_list l1, sort_list l2))
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let find_occurances l item =
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let rec loop l item acc = match l with
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| [] -> acc
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| head :: tail -> if head == item then loop tail item (acc + 1) else loop tail item acc in
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loop l item 0
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let () =
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print_endline "\nAdvent of Code 2024";
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let lines = read_lines "./bin/input.txt" in
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let rec distance l1 l2 acc =
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match (l1, l2) with
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| ([], []) -> acc
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| (h1 :: t1, h2 :: t2) ->
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distance t1 t2 (acc + if h1 > h2 then h1 - h2 else h2 - h1)
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| _, _ -> acc in
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let (l1, l2) = build_lists lines in
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let part1 = distance l1 l2 0 in
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Printf.printf "Part 1: %s\n" (string_of_int part1);
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let rec similarity l1 l2 acc =
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match l1 with
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| [] -> acc
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| head :: tail -> similarity tail l2 (acc + head * find_occurances l2 head) in
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let part2 = similarity l1 l2 0 in
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Printf.printf "Part 2: %s\n" (string_of_int part2);
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