commit 5081ea9a0f5bb09023ae957f22b1c79f40ac87db · treybastian.com/advent-of-code

+49

2024/day_02.ml

···

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       let filename = "./day_02_input.txt"

     

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       let try_read ic = try Some (input_line ic) with End_of_file -> None

     

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       let is_values_safe a b direction =

     

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         match direction with

     

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         | "up" -> a < b && abs (a - b) < 4

     

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         | "down" -> a > b && abs (a - b) < 4

     

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         | _ -> false

     

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       let direction a b = if a < b then "up" else "down"

     

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       let is_line_safe list =

     

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         let a, b = (List.hd list, List.tl list |> List.hd) in

     

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         let direction = direction a b in

     

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         List.fold_left

     

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           (fun (acc, prev) x ->

     

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             if prev > -1 then (acc && is_values_safe prev x direction, x) else (acc, x))

     

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           (true, -1) list

     

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         |> fst

     

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       let is_line_safe_part_2 list =

     

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         List.mapi

     

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           (fun i _ -> List.filteri (fun j _ -> j <> i) list |> is_line_safe)

     

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           list

     

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         |> List.exists (fun x -> x)

     

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       let calculate_safe_score ic is_line_safe =

     

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         let rec calculate acc =

     

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           match try_read ic with

     

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           | Some line -> (

     

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               match

     

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                 is_line_safe (String.split_on_char ' ' line |> List.map int_of_string)

     

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               with

     

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               | true -> calculate (acc + 1)

     

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               | false -> calculate acc)

     

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           | None ->

     

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               close_in ic;

     

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               acc

     

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         in

     

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         calculate 0

     

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       let () =

     

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         let ic = open_in filename in

     

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         calculate_safe_score ic is_line_safe

     

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         |> Printf.sprintf "Safe %d" |> print_endline;

     

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         let ic = open_in filename in

     

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         calculate_safe_score ic is_line_safe_part_2

     

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         |> Printf.sprintf "Safe %d" |> print_endline