86 lines
2.3 KiB
OCaml
86 lines
2.3 KiB
OCaml
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let input = Reuse.split_lines "inputs/day1.txt"
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let convert (s : string): int =
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let first_char = s.[0] in
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let remainder = String.sub s 1 (String.length s - 1) in
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let distance = int_of_string remainder in
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match first_char with
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| 'L' -> -distance
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| 'R' -> distance
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| _ -> raise (Invalid_argument "Invalid input")
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let count_if_zero (counter: int) (position: int) =
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if position == 0 then counter + 1 else counter
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let normalize_position (pos : int) (modulus : int) =
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let result = pos mod modulus in
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if result >= 0 then result else result + modulus
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let count_boundary_crossings (counter: int) (position: int) (movement: int) =
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let full_rotations = abs movement / 100 in
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let remaining_movement = movement mod 100 in
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let new_position = position + remaining_movement in
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let boundary_crossings =
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if (new_position >= 100 && position < 100) ||
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(new_position <= 0 && position > 0) then 1 else 0
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in
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counter + full_rotations + boundary_crossings
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let rec update (values: int list) (position: int) (counter: int) : int =
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match values with
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| [] -> counter
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| x :: xs -> let new_position = normalize_position (position + x) 100 in
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update xs new_position (count_if_zero counter new_position)
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let rec update_part2 (values: int list) (position: int) (counter: int) : int =
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match values with
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| [] -> counter
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| x :: xs -> let new_position = normalize_position (position + x) 100 in
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update_part2 xs new_position (count_boundary_crossings counter position x)
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let solve_part1 (lines: string list) : int =
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update (List.map convert lines) 50 0
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let solve_part2 (lines: string list) : int =
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update_part2 (List.map convert lines) 50 0
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let day1_part1 : int =
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solve_part1 input
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let day1_part2 : int =
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solve_part2 input
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module Tests = struct
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let test_input = "L268
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L30
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R48
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L5
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R60
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L55
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L1
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L99
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R14
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L82"
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let test_lines = String.split_on_char '\n' test_input
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let run_tests () =
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let part1_result = solve_part1 test_lines in
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let part2_result = solve_part2 test_lines in
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if part1_result <> 3 then
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failwith ("Part 1 test failed: expected 3, got " ^ string_of_int part1_result);
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if part2_result <> 8 then
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failwith ("Part 2 test failed: expected 8, got " ^ string_of_int part2_result);
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Printf.printf "All tests passed!\n"
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end
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let () = Tests.run_tests()
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