day 10: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

10.rkt

@@ -0,0 +1,147 @@
+#lang curly-fn racket
+
+(require "scripts/aoc.rkt")
+
+;; solution for day 10
+
+;; helper functions here
+
+(define (part1 input)
+  (define sorted (sort input <))
+  (define-values [_ ones threes]
+    (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 _]
+    (for/fold ([edges '()] [lst (rest is)]) ([x (in-list is)])
+      (define res3
+        (if (and (> (length lst) 2) (<= (- (third lst) 3) x))
+          (list (list x (third lst)))
+          '()))
+      (define res2
+        (if (and (> (length lst) 1) (<= (- (second lst) 3) x))
+          (list (list x (second lst)))
+          '()))
+      (define res1
+        (if (and (> (length lst) 0) (<= (- (first lst) 3) x))
+          (list (list x (first lst)))
+          '()))
+    (values (append edges res1 res2 res3) (if (empty? lst) '() (rest lst)))))
+
+  (define G (directed-graph edges))
+
+  (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]))
+
+  (count-paths G 0))
+
+; (part2 '(16
+;          10
+;          15
+;          5
+;          1
+;          11
+;          7
+;          19
+;          6
+;          12
+;          4))
+
+(module+ test
+  (require rackunit)
+  ;; tests here
+  (displayln "no tests :("))
+
+(module+ main
+  (define input (map string->number (file->lines "inputs/10")))
+  ;; part 1
+  (answer 10 1 (part1 input))
+
+  ;; part 2
+  (answer 10 2 (part2 input))
+
+  (displayln "meow"))