day 14 complete

1 files changed, 64 insertions, 0 deletions

diff --git a/2022/day-14/day-14.rkt b/2022/day-14/day-14.rkt
new file mode 100644
index 0000000..7950339
--- /dev/null
+++ b/2022/day-14/day-14.rkt
@@ -0,0 +1,64 @@
+#lang racket
+
+(require advent-of-code
+         threading
+         algorithms)
+
+(define data (fetch-aoc-input (find-session) 2022 14 #:cache #true))
+
+(define (trace-line-between-points p1 p2)
+  (match* (p1 p2)
+    [((list x y1) (list x y2))
+     (for/list ([y [in-inclusive-range (min y1 y2) (max y1 y2)]])
+       (cons x y))]
+    [((list x1 y) (list x2 y))
+     (for/list ([x [in-inclusive-range (min x1 x2) (max x1 x2)]])
+       (cons x y))]))
+
+(define all-coordinates
+  (apply append
+         (for/list ([formation (in-list (string-split data "\n"))])
+           (define coord-list
+             (for/list ([coord-pair (in-list (string-split formation " -> "))])
+               (for/list ([coord (in-list (string-split coord-pair ","))])
+                 (string->number coord))))
+           (apply append (adjacent-map trace-line-between-points coord-list)))))
+
+(define rock-structures-hash
+  (for/hash ([p (in-list all-coordinates)])
+    (values p 'rock)))
+
+(define max-vertical-distance (~>> all-coordinates (argmax cdr) cdr add1))
+
+(define (open? h x y)
+  (not (hash-has-key? h (cons x y))))
+
+;; part 1
+(define (trace-grain h [pos (cons 500 0)])
+  (match-define (cons x y) pos)
+  (cond
+    [(> y max-vertical-distance) 'break]
+    [(open? h x (add1 y)) (trace-grain h (cons x (add1 y)))]
+    [(open? h (sub1 x) (add1 y)) (trace-grain h (cons (sub1 x) (add1 y)))]
+    [(open? h (add1 x) (add1 y)) (trace-grain h (cons (add1 x) (add1 y)))]
+    [else (hash-set h (cons x y) 'sand)]))
+
+(for/fold ([h rock-structures-hash] [grains 0] #:result grains) ([_ (in-naturals 1)])
+  (define h* (trace-grain h))
+  #:break (eq? h* 'break)
+  (values h* (add1 grains)))
+
+;; part 2
+(define (trace-grain* h [pos (cons 500 0)])
+  (match-define (cons x y) pos)
+  (cond
+    [(= y max-vertical-distance) (hash-set h (cons x y) 'sand)]
+    [(open? h x (add1 y)) (trace-grain* h (cons x (add1 y)))]
+    [(open? h (sub1 x) (add1 y)) (trace-grain* h (cons (sub1 x) (add1 y)))]
+    [(open? h (add1 x) (add1 y)) (trace-grain* h (cons (add1 x) (add1 y)))]
+    [else (hash-set h (cons x y) 'sand)]))
+
+(for/fold ([h rock-structures-hash] [grains 0] #:result grains) ([_ (in-naturals 1)])
+  #:break (not (open? h 500 0))
+  (define h* (trace-grain* h))
+  (values h* (add1 grains)))