solve day 11 :)

exe/main.ml

@@ -10,5 +10,6 @@ let () =
   Day7.print ();
   Day8.print ();
   Day9.print ();
-  Day10.print ()
+  Day10.print ();
+  Day11.print ()
 ;;

inputs/day11.tt

@@ -1,146 +1,55 @@
-addx 15
-addx -11
-addx 6
-addx -3
-addx 5
-addx -1
-addx -8
-addx 13
-addx 4
-noop
-addx -1
-addx 5
-addx -1
-addx 5
-addx -1
-addx 5
-addx -1
-addx 5
-addx -1
-addx -35
-addx 1
-addx 24
-addx -19
-addx 1
-addx 16
-addx -11
-noop
-noop
-addx 21
-addx -15
-noop
-noop
-addx -3
-addx 9
-addx 1
-addx -3
-addx 8
-addx 1
-addx 5
-noop
-noop
-noop
-noop
-noop
-addx -36
-noop
-addx 1
-addx 7
-noop
-noop
-noop
-addx 2
-addx 6
-noop
-noop
-noop
-noop
-noop
-addx 1
-noop
-noop
-addx 7
-addx 1
-noop
-addx -13
-addx 13
-addx 7
-noop
-addx 1
-addx -33
-noop
-noop
-noop
-addx 2
-noop
-noop
-noop
-addx 8
-noop
-addx -1
-addx 2
-addx 1
-noop
-addx 17
-addx -9
-addx 1
-addx 1
-addx -3
-addx 11
-noop
-noop
-addx 1
-noop
-addx 1
-noop
-noop
-addx -13
-addx -19
-addx 1
-addx 3
-addx 26
-addx -30
-addx 12
-addx -1
-addx 3
-addx 1
-noop
-noop
-noop
-addx -9
-addx 18
-addx 1
-addx 2
-noop
-noop
-addx 9
-noop
-noop
-noop
-addx -1
-addx 2
-addx -37
-addx 1
-addx 3
-noop
-addx 15
-addx -21
-addx 22
-addx -6
-addx 1
-noop
-addx 2
-addx 1
-noop
-addx -10
-noop
-noop
-addx 20
-addx 1
-addx 2
-addx 2
-addx -6
-addx -11
-noop
-noop
-noop
+Monkey 0:
+  Starting items: 97, 81, 57, 57, 91, 61
+  Operation: new = old * 7
+  Test: divisible by 11
+    If true: throw to monkey 5
+    If false: throw to monkey 6
+
+Monkey 1:
+  Starting items: 88, 62, 68, 90
+  Operation: new = old * 17
+  Test: divisible by 19
+    If true: throw to monkey 4
+    If false: throw to monkey 2
+
+Monkey 2:
+  Starting items: 74, 87
+  Operation: new = old + 2
+  Test: divisible by 5
+    If true: throw to monkey 7
+    If false: throw to monkey 4
+
+Monkey 3:
+  Starting items: 53, 81, 60, 87, 90, 99, 75
+  Operation: new = old + 1
+  Test: divisible by 2
+    If true: throw to monkey 2
+    If false: throw to monkey 1
+
+Monkey 4:
+  Starting items: 57
+  Operation: new = old + 6
+  Test: divisible by 13
+    If true: throw to monkey 7
+    If false: throw to monkey 0
+
+Monkey 5:
+  Starting items: 54, 84, 91, 55, 59, 72, 75, 70
+  Operation: new = old * old
+  Test: divisible by 7
+    If true: throw to monkey 6
+    If false: throw to monkey 3
+
+Monkey 6:
+  Starting items: 95, 79, 79, 68, 78
+  Operation: new = old + 3
+  Test: divisible by 3
+    If true: throw to monkey 1
+    If false: throw to monkey 3
+
+Monkey 7:
+  Starting items: 61, 97, 67
+  Operation: new = old + 4
+  Test: divisible by 17
+    If true: throw to monkey 0
+    If false: throw to monkey 5

src/day11.ml

@@ -0,0 +1,83 @@
+open Containers
+
+type monkey =
+  { mutable items : int list
+  ; mutable inspected : int
+  ; operation : int -> int
+  ; test : int -> int
+  ; test_num : int
+  }
+
+let parse_monkeys () =
+  let lines = Utils.lines_of_input 11 in
+  let rec parse lines monkeys =
+    let lines = List.drop_while (String.equal "") lines in
+    let lines, rest = List.take_drop_while Fun.(String.equal "" %> not) lines in
+    let lines = List.map Fun.(String.trim %> String.split ~by:" ") lines in
+    match lines with
+    | [ [ "Monkey"; _ ]
+      ; "Starting" :: "items:" :: items
+      ; [ "Operation:"; "new"; "="; "old"; op; op_num ]
+      ; [ "Test:"; "divisible"; "by"; test_num ]
+      ; [ "If"; "true:"; "throw"; "to"; "monkey"; if_true ]
+      ; [ "If"; "false:"; "throw"; "to"; "monkey"; if_false ]
+      ] ->
+      let items =
+        List.map Fun.(String.replace ~which:`All ~sub:"," ~by:"" %> int_of_string) items
+      in
+      let op = if String.equal op "+" then ( + ) else ( * ) in
+      let operation =
+        match op_num with
+        | "old" -> fun old -> op old old
+        | num -> fun old -> op old @@ int_of_string num
+      in
+      let test_num = int_of_string test_num in
+      let if_true = int_of_string if_true in
+      let if_false = int_of_string if_false in
+      let test score = if Int.(score mod test_num) = 0 then if_true else if_false in
+      let monkey = { items; operation; test; test_num; inspected = 0 } in
+      parse rest (monkey :: monkeys)
+    | _ -> monkeys
+  in
+  Array.of_list @@ List.rev @@ parse lines []
+;;
+
+let throw item monkey = monkey.items <- List.append [ item ] monkey.items
+
+let round monkies manageable =
+  let divisor = Array.fold_left (fun acc monkey -> acc * monkey.test_num) 1 monkies in
+  let destress score = if manageable then score / 3 else Int.(score mod divisor) in
+  monkies
+  |> Array.iter (fun monkey ->
+    monkey.items
+    |> List.iter (fun item ->
+      let item = destress @@ monkey.operation item in
+      let throw_to = monkey.test item in
+      throw item monkies.(throw_to));
+    monkey.inspected <- monkey.inspected + List.length monkey.items;
+    monkey.items <- [])
+;;
+
+let solve rounds manageable =
+  let monkies = parse_monkeys () in
+  for _ = 1 to rounds do
+    round monkies manageable
+  done;
+  monkies
+  |> Array.to_list
+  |> List.map (fun monkey -> monkey.inspected)
+  |> List.sort Int.compare
+  |> List.rev
+  |> List.take 2
+  |> List.reduce ( * )
+  |> Option.get_exn_or "aoc goofed up the input"
+;;
+
+let part1 () = solve 20 true
+let part2 () = solve 10_000 false
+
+let print () =
+  Printf.(
+    printf "Day 11.1: %d\n" @@ part1 ();
+    printf "Day 11.2: %d\n" @@ part2 ())
+;;