path: root/day2.ml

#use "topfind";;
#thread;;
#require "core";;
#require "stdio";;
#require "csv";;

open Core
open Stdio

let spreadsheet = Csv.load ~separator:'\t' "day2.txt"
                  |> List.map ~f:(List.map ~f:int_of_string)

let minmax = List.fold_left
               ~init:(Int.max_value, Int.min_value)
               ~f:(fun (lmin, lmax) x -> (min x lmin, max x lmax))

let part1 l = List.map ~f:minmax l
              |> List.map ~f:(fun (lmin, lmax) -> lmax - lmin)
              |> List.fold_left ~f:(+) ~init:0

let rec dividend row =
  let divisible a b =
    a mod b = 0 || b mod a = 0 in
  let divide a b =
    if a mod b = 0 then a/b else b/a in

  match row with
  | [] -> 0
  | h::t ->
     match List.find t ~f:(divisible h) with
     | Some x -> divide h x
     | None -> dividend t

let part2 l = List.map ~f:dividend l
              |> List.fold_left ~f:(+) ~init:0

let () =
  Printf.printf "%d\n" (part1 spreadsheet);
  Printf.printf "%d\n" (part2 spreadsheet)