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71 lines
2.3 KiB
OCaml
71 lines
2.3 KiB
OCaml
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(* Common util. Should probably put this in a module or something.. *)
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let get_one_line file =
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try Some (input_line file) with
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End_of_file -> None
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let get_lines file =
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let rec input lines =
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match get_one_line file with
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Some line -> input (line :: lines)
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| None -> List.rev lines
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in input []
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let read_file file =
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let channel = open_in(file) in
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get_lines channel
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let explode s = (* convert a string to a list of chars *)
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let rec exp i l =
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if i < 0 then l else exp (i - 1) (s.[i] :: l) in
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exp (String.length s - 1) []
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let implode cl = String.concat "" (List.map (String.make 1) cl)
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let (<<) f g x = f(g(x)) (* how is 'compose' not in the standard library.. *)
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let (>>) f g x = g(f(x))
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let string_of_char = String.make 1
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(* --- *)
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let fix_lines glue_char lines = (* puts each group on 1 line *)
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let glue s = if String.equal s "" then "\n" else glue_char in (* which char to concat the lines *)
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let fix_line acc cur = acc ^ (glue cur) ^ cur in
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List.fold_left fix_line "" lines
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let dedup =
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explode >> (* string -> char list *)
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List.fold_left (fun acc x -> if String.contains acc x then acc else acc ^ (string_of_char x)) ""
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let intersection group = (* find the chars common to all individuals in a group *)
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List.fold_left (^) "" group (* *all* of the chars among individuals *)
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|> dedup (* deduped *)
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|> explode (* string to char list *)
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|> List.filter (fun c -> List.for_all (fun g -> String.contains g c) group) (* check each char among each individual for membership *)
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|> implode (* turn it back into a string *)
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let () =
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let file = read_file "day6.txt" in
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let any_sum = file
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|> fix_lines "" (* put each group on one line *)
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|> String.split_on_char '\n' (* convert to list *)
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|> List.map dedup (* remove dups *)
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|> List.map String.length (* make list of lengths *)
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|> List.fold_left (+) 0 (* sum list *)
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in
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let all_sum = file
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|> fix_lines " " (* keep spaces between individuals *)
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|> String.split_on_char '\n'
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|> List.map String.trim
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|> List.map (String.split_on_char ' ') (* each line now is a list of groups *)
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|> List.map intersection (* list of strings with intersecting chars *)
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|> List.map String.length (* list of lengths *)
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|> List.fold_left (+) 0 (* sum list *)
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in
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Printf.printf "any_sum %i\n" any_sum;
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Printf.printf "all_sum %i\n" all_sum;
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