1 files changed, 0 insertions, 59 deletions
diff --git a/aoc2021/day-09/day-09.rkt b/aoc2021/day-09/day-09.rkt
deleted file mode 100644
index d550a9e..0000000
--- a/aoc2021/day-09/day-09.rkt
+++ /dev/null
@@ -1,59 +0,0 @@
-#lang racket
-
-(require threading
-         "../../jj-aoc.rkt")
-
-(define sea-floor-data
-  (for/vector ([l (in-lines (open-day 9))] #:unless (equal? l ""))
-    (~>> l string->list (map (λ~>> ~a string->number)) list->vector)))
-
-(define max-rows (vector-length sea-floor-data))
-(define max-cols (vector-length (vector-ref sea-floor-data 0)))
-(define-values (min-rows min-cols) (values 0 0))
-
-(define (vector2d-ref vec coord)
-  (match-define `(,r ,c) coord)
-  (~> vec (vector-ref r) (vector-ref c)))
-
-(define (adjacent coords)
-  (match-define `(,r ,c) coords)
-  `((,(add1 r) ,c) (,(sub1 r) ,c) (,r ,(add1 c)) (,r ,(sub1 c))))
-
-(define (valid-coordinate coord)
-  (match-define `(,r ,c) coord)
-  (and (>= r min-rows) (< r max-rows) (>= c min-cols) (< c max-cols)))
-
-;; part 1
-(define (lowest-point? vec coord)
-  (for*/and ([neighbor (in-list (adjacent coord))] #:when (valid-coordinate neighbor))
-    (< (vector2d-ref vec coord) (vector2d-ref vec neighbor))))
-
-(for*/sum ([r (in-range min-rows max-rows)] [c (in-range min-cols max-cols)]
-                                            [coord (in-value `(,r ,c))]
-                                            #:when (lowest-point? sea-floor-data coord))
-          (add1 (vector2d-ref sea-floor-data coord)))
-
-;; part 2
-;; all the basins are bordered by the edges or by ridges of elevation 9,
-;; so it's not really necessary to start at a low point
-(define walked (make-hash))
-
-(define (walkable? vec coord)
-  (and (< (vector2d-ref vec coord) 9) (not (hash-has-key? walked coord))))
-
-(define (walk-the-basin vec coord)
-  (cond
-    [(walkable? vec coord)
-     (hash-set! walked coord 'visited)
-     (add1 (for/sum [(neighbor (in-list (adjacent coord))) #:when (valid-coordinate neighbor)]
-                    (walk-the-basin vec neighbor)))]
-    [else 0]))
-
-(define basins
-  (for*/list ([r (in-range min-rows max-rows)]
-              [c (in-range min-cols max-cols)]
-              [coord (in-value `(,r ,c))]
-              #:when (walkable? sea-floor-data coord))
-    (walk-the-basin sea-floor-data coord)))
-
-(~> basins (sort >) (take 3) (apply * _))