diff options
| -rw-r--r-- | 2021/day-13/day-13.rkt | 64 | ||||
| -rw-r--r-- | jj-aoc.rkt | 2 |
2 files changed, 65 insertions, 1 deletions
diff --git a/2021/day-13/day-13.rkt b/2021/day-13/day-13.rkt new file mode 100644 index 0000000..60cb95f --- /dev/null +++ b/2021/day-13/day-13.rkt @@ -0,0 +1,64 @@ +#lang racket +(require "../../jj-aoc.rkt" + threading) + +(define (make-pt x y) + (hash 'x x 'y y)) +(struct fold (dir loc) #:transparent) +(define (make-fold dir loc) + (fold (string->symbol dir) + (string->number loc))) + +(define data (port->lines (open-day 13 2021))) +(define-values (points-list folds-list) (splitf-at data (λ~> (equal? "") not))) + +(define pts + (for/set ([p (in-list points-list)]) + (~> p + (string-split ",") + (map string->number _) + (apply make-pt _)))) + +(define folds + (for/list ([f (in-list (rest folds-list))]) + (~>> f + (regexp-match #px"fold along (.)=(.*)") + rest + (apply make-fold)))) + +(define (fold-over f pts) + (define dir (fold-dir f)) + (define loc (fold-loc f)) + (for/set ([p (in-set pts)]) + (cond + [(> (hash-ref p dir) loc) (hash-update p dir (λ (l) (- (* 2 loc) l)))] + [else p]))) + +;; part 1 +(~>> pts + (fold-over (first folds)) + set-count) + +;; part 2 +(define final-fold + (for/fold ([p pts]) + ([f (in-list folds)]) + (fold-over f p))) + +(for/list ([y (in-range 6)]) + (~>> (for/list ([x (in-range 39)]) + (if (set-member? final-fold (hash 'x x 'y y)) + #\█ + #\space)) + (apply string) + println)) + +#| +for this data set, the result looks like +" ██ █ █ ██ ██ ███ ██ ██ █ █" +"█ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █" +"█ █ ████ █ █ █ █ █ █ █ █ █" +"████ █ █ █ ██ █ ███ █ ██ ████ █ █" +"█ █ █ █ █ █ █ █ █ █ █ █ █ █ █" +"█ █ █ █ ███ ██ █ ███ █ █ ██ " +|#
\ No newline at end of file @@ -3,4 +3,4 @@ (provide open-day) (define (open-day n [year 2021]) - (open-aoc-input (find-session) year n #:cache (string->path "../../cache")))
\ No newline at end of file + (open-aoc-input (find-session) year n #:cache (string->path "./cache")))
\ No newline at end of file |