1 files changed, 41 insertions, 74 deletions

diff --git a/2021/day-16/day-16.rkt b/2021/day-16/day-16.rkt
index 4183ab9..86083ef 100644
--- a/2021/day-16/day-16.rkt
+++ b/2021/day-16/day-16.rkt
@@ -3,39 +3,27 @@
          bitsyntax
          threading)
 
-(struct packet (version type type-id contents len)
-  #:transparent)
+(struct packet (version type type-id contents len) #:transparent)
 
 (define (BITS->bitstring str)
-  (integer->bit-string (string->number str 16)
-                       (* 4 (string-length str))
-                       #true))
+  (integer->bit-string (string->number str 16) (* 4 (string-length str)) #true))
 
-(define data
-  (~> (open-day 16 2021)
-    port->string
-    string-trim
-    BITS->bitstring))
+(define data (~> (open-day 16 2021) port->string string-trim BITS->bitstring))
 
 (define (get-literal-contents bitstr)
   (for/fold ([assembled (bit-string)]
              [remaining bitstr]
              [total-length 6]
              [complete? #f]
-             #:result (values (bit-string->integer assembled #t #f)
-                              remaining
-                              total-length))
-            ([_ (in-naturals)]
-             #:break complete?)
+             #:result (values (bit-string->integer assembled #t #f) remaining total-length))
+            ([_ (in-naturals)] #:break complete?)
     (bit-string-case remaining
                      ([(= 1 :: bits 1) (number :: bits 4) (remaining :: binary)]
                       (values (bit-string-append assembled (integer->bit-string number 4 #t))
                               remaining
                               (+ total-length 5)
                               #f))
-                     ([(= 0 :: bits 1)
-                       (number :: bits 4)
-                       (remaining :: binary)]
+                     ([(= 0 :: bits 1) (number :: bits 4) (remaining :: binary)]
                       (values (bit-string-append assembled (integer->bit-string number 4 #t))
                               remaining
                               (+ total-length 5)
@@ -43,67 +31,50 @@
 
 (define (get-type-0-contents cnt bitstr [acc '()] [len 0])
   (cond
-    [(<= cnt 0) (values (reverse acc)
-                        bitstr
-                        len)]
-    [else (define-values (packet remaining)
-            (identify-next-packet bitstr))
-          (get-type-0-contents (- cnt (packet-len packet))
-                               remaining
-                               (cons packet acc)
-                               (+ len (packet-len packet)))]))
+    [(<= cnt 0) (values (reverse acc) bitstr len)]
+    [else
+     (define-values (packet remaining) (identify-next-packet bitstr))
+     (get-type-0-contents (- cnt (packet-len packet))
+                          remaining
+                          (cons packet acc)
+                          (+ len (packet-len packet)))]))
 
 (define (get-type-1-contents cnt bitstr [acc '()] [len 0])
   (cond
-    [(= cnt 0) (values (reverse acc)
-                       bitstr
-                       len)]
-    [else (define-values (packet remaining)
-            (identify-next-packet bitstr))
-          (get-type-1-contents (sub1 cnt)
-                               remaining
-                               (cons packet acc)
-                               (+ len (packet-len packet)))]))
+    [(= cnt 0) (values (reverse acc) bitstr len)]
+    [else
+     (define-values (packet remaining) (identify-next-packet bitstr))
+     (get-type-1-contents (sub1 cnt) remaining (cons packet acc) (+ len (packet-len packet)))]))
 
 (define (identify-next-packet bitstr)
-  (bit-string-case bitstr
-                   ([(packet-version :: bits 3)
-                     (= 4 :: bits 3)
-                     (remaining :: binary)]
-                    (define-values (n now-remaining len)
-                      (get-literal-contents remaining))
-                    (values (packet packet-version 'literal 4 n len)
-                            now-remaining))
-
-                   ([(packet-version :: bits 3)
-                     (type-id :: bits 3)
-                     (= 0 :: bits 1)
-                     (subpacket-length :: bits 15)
-                     (remaining :: binary)]
-                    (define-values (contents now-remaining sublength)
-                      (get-type-0-contents subpacket-length remaining))
-                    (values (packet packet-version 'operator type-id contents (+ 22 sublength))
-                            now-remaining))
-
-                   ([(packet-version :: bits 3)
-                     (type-id :: bits 3)
-                     (= 1 :: bits 1)
-                     (subpacket-count :: bits 11)
-                     (remaining :: binary)]
-                    (define-values (contents now-remaining sublength)
-                      (get-type-1-contents subpacket-count remaining))
-                    (values (packet packet-version 'operator type-id contents (+ 22 sublength))
-                            now-remaining))))
-
-(match-define-values (outer-packet n)
-  (identify-next-packet data))
+  (bit-string-case
+   bitstr
+   ([(packet-version :: bits 3) (= 4 :: bits 3) (remaining :: binary)]
+    (define-values (n now-remaining len) (get-literal-contents remaining))
+    (values (packet packet-version 'literal 4 n len) now-remaining))
+   ([(packet-version :: bits 3)
+     (type-id :: bits 3)
+     (= 0 :: bits 1)
+     (subpacket-length :: bits 15)
+     (remaining :: binary)]
+    (define-values (contents now-remaining sublength)
+      (get-type-0-contents subpacket-length remaining))
+    (values (packet packet-version 'operator type-id contents (+ 22 sublength)) now-remaining))
+   ([(packet-version :: bits 3)
+     (type-id :: bits 3)
+     (= 1 :: bits 1)
+     (subpacket-count :: bits 11)
+     (remaining :: binary)]
+    (define-values (contents now-remaining sublength) (get-type-1-contents subpacket-count remaining))
+    (values (packet packet-version 'operator type-id contents (+ 22 sublength)) now-remaining))))
+
+(match-define-values (outer-packet n) (identify-next-packet data))
 
 ;; part 1
 (define (packet-sum-version p)
   (match p
     [(packet v 'literal _type-id _contents _len) v]
-    [(packet v 'operator _type-id ps _len)
-     (foldl (λ (p acc) (+ acc (packet-sum-version p))) v ps)]))
+    [(packet v 'operator _type-id ps _len) (foldl (λ (p acc) (+ acc (packet-sum-version p))) v ps)]))
 
 (packet-sum-version outer-packet)
 
@@ -121,10 +92,6 @@
 (define packet-eval
   (match-lambda
     [(packet _v 'literal _type-id n _len) n]
-    [(packet _v 'operator type-id ps _len)
-     (~>> ps
-          (map packet-eval)
-          (apply (packet-f type-id)))]))
+    [(packet _v 'operator type-id ps _len) (~>> ps (map packet-eval) (apply (packet-f type-id)))]))
 
 (packet-eval outer-packet)
-