solutions up to day 4

1 files changed, 38 insertions, 0 deletions

diff --git a/day4.ml b/day4.ml
new file mode 100644
index 0000000..e058aec
--- /dev/null
+++ b/day4.ml
@@ -0,0 +1,38 @@
+#use "topfind";;
+#thread;;
+#require "core";;
+#require "stdio";;
+
+open Core
+open Stdio
+
+let passphrases = In_channel.read_lines "day4.txt"
+                  |> List.map ~f:(fun x -> String.strip x |> String.split ~on:' ')
+
+
+let passphrase_set_lengths p =
+  let toSet strings =
+    List.fold ~f:Set.add ~init:(Set.empty (module String)) strings in
+  List.map ~f:toSet p |> List.map ~f:Set.length
+
+let passphrase_lengths = List.map ~f:List.length
+
+let rec has_anagram passphrase =
+  let string_to_set =
+    String.fold ~f:Set.add ~init:(Set.empty (module Char)) in
+  let anagram a b =
+    Set.equal (string_to_set a) (string_to_set b) in
+  match passphrase with
+  | [] -> false
+  | h::t ->
+     match List.find t ~f:(anagram h) with
+     | Some x -> true
+     | None -> has_anagram t
+
+let () =
+  let pairs = List.zip_exn (passphrase_set_lengths passphrases) (passphrase_lengths passphrases) in
+  let valid_count = List.fold ~f:(fun acc (x, y) -> if x = y then acc+1 else acc) ~init:0 pairs in
+  Printf.printf "%d\n" valid_count;
+
+  let anagram_count = List.fold ~f:(fun acc x -> if has_anagram x then acc else acc + 1) ~init:0 passphrases in
+  Printf.printf "%d\n" anagram_count