1 files changed, 0 insertions, 76 deletions
diff --git a/2022/day-09/day-09.rkt b/2022/day-09/day-09.rkt
deleted file mode 100644
index 0390d2e..0000000
--- a/2022/day-09/day-09.rkt
+++ /dev/null
@@ -1,76 +0,0 @@
-#lang racket
-(require advent-of-code
-         threading)
-
-(struct cmd (dir amt))
-(struct posn (x y) #:transparent)
-
-(define moves
-  (~> (fetch-aoc-input (find-session) 2022 9)
-      (string-split "\n")
-      (map (λ~> (string-split _)
-                (match _
-                  [(list dir amt) (cmd (string->symbol dir) (string->number amt))]))
-           _)))
-
-(define (move-head p dir)
-  (match-define (posn x y) p)
-  (match dir
-    ['U (posn x (add1 y))]
-    ['D (posn x (sub1 y))]
-    ['R (posn (add1 x) y)]
-    ['L (posn (sub1 x) y)]))
-
-(define (avg n m)
-  (/ (+ n m) 2))
-
-(define (manhattan-distance p1 p2)
-  (match-define (posn x1 y1) p1)
-  (match-define (posn x2 y2) p2)
-  (+ (abs (- x2 x1)) (abs (- y2 y1))))
-
-(define (follow-head head tail)
-  (match-define (posn hx hy) head)
-  (match-define (posn tx ty) tail)
-
-  (case (manhattan-distance head tail)
-    [(0 1) tail]
-    [(2 4)
-     (cond
-       [(and (= 1 (abs (- hx tx)) (abs (- hy ty)))) tail]
-       [else (posn (avg hx tx) (avg hy ty))])]
-    [(3)
-     (cond
-       [(= 2 (abs (- hx tx))) (posn (avg hx tx) hy)]
-       [(= 2 (abs (- hy ty))) (posn hx (avg hy ty))])]))
-
-;; part 1
-(for*/fold ([head (posn 0 0)] [tail (posn 0 0)] [tail-posns (set)] #:result (set-count tail-posns))
-           ([move (in-list moves)] #:do [(match-define (cmd dir amt) move)] [_ (in-range amt)])
-  (define new-head (move-head head dir))
-  (define new-tail (follow-head new-head tail))
-  (values new-head new-tail (set-add tail-posns new-tail)))
-
-;; part 2
-(for*/fold ([knots (make-list 10 (posn 0 0))] [tail-posns (set)] #:result (set-count tail-posns))
-           ([move (in-list moves)] #:do [(match-define (cmd dir amt) move)] [_ (in-range amt)])
-  (define updated-knots
-    (for/fold ([knots-list (list (move-head (first knots) dir))])
-              ([following-knot (in-list (rest knots))])
-      (cons (follow-head (car knots-list) following-knot) knots-list)))
-  (values (reverse updated-knots) (set-add tail-posns (first updated-knots))))
-
-;; refactor: part 1 and 2 combined
-(define (follow-tail move-list rope-length)
-  (for*/fold ([knots (make-list rope-length (posn 0 0))]
-              [tail-posns (set)]
-              #:result (set-count tail-posns))
-             ([move (in-list move-list)] #:do [(match-define (cmd dir amt) move)] [_ (in-range amt)])
-    (define updated-knots
-      (for/fold ([knots-list (list (move-head (first knots) dir))])
-                ([following-knot (in-list (rest knots))])
-        (cons (follow-head (car knots-list) following-knot) knots-list)))
-    (values (reverse updated-knots) (set-add tail-posns (first updated-knots)))))
-
-(time (follow-tail moves 2))
-(time (follow-tail moves 10))