89 lines
2.8 KiB
OCaml
89 lines
2.8 KiB
OCaml
open Printf;;
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open Map;;
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let rec list_of_lines in_file =
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try
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let line = input_line in_file in
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line :: list_of_lines(in_file)
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with End_of_file ->
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close_in in_file;
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[]
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let rec parse_int_list sep str =
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let list1 = (List.filter (fun a -> String.length a != 0) (String.split_on_char sep str)) in
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List.map int_of_string list1
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(* Ordering map is a map that indexes int and maps it into a set of ints,
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the indexed element must be before each of the elements of the mapped set*)
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module IntMap = Map.Make(Int)
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module IntSet = Set.Make(Int)
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let rec parse_ordering lines ordering_map =
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match lines with
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| head :: tail ->
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if String.length head > 0 then
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let elems = parse_int_list '|' head in
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let e1 = List.hd elems in
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let e2 = List.nth elems 1 in
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let update_fun prev =
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match prev with
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| Some set -> Some (IntSet.add e1 set)
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| None -> Some (IntSet.add e1 IntSet.empty) in
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let new_map = IntMap.update e2 update_fun ordering_map in
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parse_ordering tail new_map
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else
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(tail, ordering_map)
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| _ -> (lines, ordering_map)
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let parse in_file =
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let lines = list_of_lines in_file in
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let lines_rest, ordering_map = parse_ordering lines IntMap.empty in
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let entries = List.map (fun str -> List.rev @@ parse_int_list ',' str) lines_rest in
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(ordering_map, entries)
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let rec is_good ordering_map already_appeared entry =
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match entry with
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| head :: tail -> begin
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let new_already_appeared = IntSet.add head already_appeared in
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match IntMap.find_opt head ordering_map with
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| Some set ->
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let intersect = IntSet.inter set new_already_appeared in
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if IntSet.is_empty intersect then
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is_good ordering_map new_already_appeared tail
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else
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false
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| None ->
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is_good ordering_map new_already_appeared tail
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end
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| _ -> true
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let get_middle_element lst =
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List.nth lst (List.length lst / 2)
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let ordering_less_than ordering_map x1 x2 =
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match IntMap.find_opt x1 ordering_map with
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| Some x1_set -> x1_set |> IntSet.find_opt x2 |> Option.is_some
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| None -> false
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let ordering_function ordering_map x1 x2 =
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if ordering_less_than ordering_map x1 x2 then (-1)
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else if ordering_less_than ordering_map x2 x1 then 1
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else 0
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let fix_ordering ordering_map lst =
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List.sort (ordering_function ordering_map) lst
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let rec summarise_entries ordering_map acc elem =
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if is_good ordering_map IntSet.empty elem then
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let v = get_middle_element elem in
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(fst acc + v, snd acc)
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else
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let new_elem = fix_ordering ordering_map elem in
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let v = get_middle_element new_elem in
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(fst acc, snd acc + v)
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let () =
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let f = open_in "input.txt" in
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let ordering_map, entries = parse f in
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let result, result2 = List.fold_left (summarise_entries ordering_map) (0, 0) entries in
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printf "%d\n%d\b" result result2 |