day 10: bit of cleanup

10.rkt

@@ -12,79 +12,8 @@
     (for/fold ([prev 0] [ones 0] [threes 0]) ([x (in-list sorted)])
       (values x (+ ones (if (= 1 (- x prev)) 1 0))
               (+ threes (if (= 3 (- x prev)) 1 0)))))
-  ; (displayln ones)
-  ; (displayln (add1 threes))
   (* ones (add1 threes)))
 
-; (part1 '(16
-;          10
-;          15
-;          5
-;          1
-;          11
-;          7
-;          19
-;          6
-;          12
-;          4))
-; (part1 '(28
-;          33
-;          18
-;          42
-;          31
-;          14
-;          46
-;          20
-;          48
-;          47
-;          24
-;          23
-;          49
-;          45
-;          19
-;          38
-;          39
-;          11
-;          1
-;          32
-;          25
-;          35
-;          8
-;          17
-;          7
-;          9
-;          4
-;          2
-;          34
-;          10
-;          3))
-
-  ; (struct res [val ones threes] #:transparent)
-  ; (define (step input [prev 0])
-  ;   ; (printf "~a ~a ~a\n" (first input) (second input) (third input))
-  ;   (define res3
-  ;     (if (and (> (length input) 2) (<= (- (third input) 3) prev))
-  ;       (step (cons (first input) (rest (rest (rest input)))) (third input))
-  ;       #f))
-  ;   (define res2
-  ;     (if (and (> (length input) 1) (<= (- (second input) 3) prev))
-  ;       (step (rest (rest input)) (second input))
-  ;       #f))
-  ;   (define res1
-  ;     (if (and (> (length input) 0) (<= (- (first input) 3) prev))
-  ;       (step (rest input) (first input))
-  ;       #f))
-  ;   (define n1 (and res1 (res-val res1)))
-  ;   (define n2 (and res2 (res-val res2)))
-  ;   (define n3 (and res3 (res-val res3)))
-  ;   (cond
-  ;     [(and res1 (and res2 (>= n1 n2)) (and res3 (>= n1 n3))) (res (add1 n1) (add1 (res-ones res1)) (res-threes res1))]
-  ;     [(and res2 (and res1 (>= n2 n1)) (and res3 (>= n2 n3))) (res (add1 n1) (res-ones res1) (res-threes res1))]
-  ;     [(and res3 (and res1 (>= n3 n1)) (and res2 (>= n3 n2))) (res (add1 n1) (res-ones res1) (add1 (res-threes res1)))]
-  ;     [else (res 1 0 0)]))
-  ; (define res_ (step sorted))
-  ; (* (res-ones res_) (res-threes res_)))
-
 (define (part2 input)
   (define is (cons 0 (sort input <)))
   (define-values [edges _]
@@ -107,34 +36,18 @@
 
   (define wanted (last is))
 
-  (define memo (make-hash))
-  (define (count-paths G node)
-    (cond [(hash-has-key? memo node) (hash-ref memo node)]
-          [(= node wanted) 1]
-          [else
-            (define ans (for/sum ([x (in-neighbors G node)])
-                          (count-paths G x)))
-            (hash-set! memo node ans)
-            ans]))
+  (define/memoized (count-paths node)
+    (cond [(= node wanted) 1]
+          [else (for/sum ([x (in-neighbors G node)])
+                  (count-paths x))]))
 
-  (count-paths G 0))
-
-; (part2 '(16
-;          10
-;          15
-;          5
-;          1
-;          11
-;          7
-;          19
-;          6
-;          12
-;          4))
+  (count-paths 0))
 
 (module+ test
   (require rackunit)
-  ;; tests here
-  (displayln "no tests :("))
+  (check-equal?
+    8 (part2
+        '(16 10 15 5 1 11 7 19 6 12 4))))
 
 (module+ main
   (define input (map string->number (file->lines "inputs/10")))

scripts/aoc.rkt

@@ -3,7 +3,8 @@
 ;; utilities for every challenge script
 
 (require "aoc-lib.rkt" threading syntax/parse/define (for-syntax racket/syntax) graph)
-(provide answer dbg (all-from-out threading syntax/parse/define graph)
+(provide answer dbg memoize define/memoized
+         (all-from-out threading syntax/parse/define graph)
          (for-syntax (all-from-out racket/syntax)))
 
 ;; in-expression debug print, uwu
@@ -11,6 +12,15 @@
   (pretty-write x)
   x)
 
+;; makes a memoization wrapper around a function
+(define (memoize func)
+  (define memo (make-hash))
+  (lambda (arg)
+    (hash-ref! memo arg (λ () (func arg)))))
+
+(define-simple-macro (define/memoized (name:id arg:id) body:expr ...+)
+  (define name (memoize (λ (arg) body ...))))
+
 ;; submit a solution to the server if not already submitted
 (define (answer day part answer)
   (printf "answer ~a.~a: ~s\n" day part answer)