diff options
Diffstat (limited to 'aoc2023-racket/day-03/day-03.rkt')
-rw-r--r-- | aoc2023-racket/day-03/day-03.rkt | 72 |
1 files changed, 0 insertions, 72 deletions
diff --git a/aoc2023-racket/day-03/day-03.rkt b/aoc2023-racket/day-03/day-03.rkt deleted file mode 100644 index 60e81a6..0000000 --- a/aoc2023-racket/day-03/day-03.rkt +++ /dev/null @@ -1,72 +0,0 @@ -#lang racket - -(require advent-of-code - threading) - -(struct posn (x y) #:transparent) -(struct part (n posns) #:transparent) - -(define (make-board port) - (for*/hash ([(row y) (in-indexed (port->lines port))] - [(col x) (in-indexed (string->list row))] - #:unless (equal? col #\.)) - (define v - (cond - [(string->number (string col))] - [(equal? col #\*) 'gear] - [else 'other])) - (values (posn x y) v))) - -(define board (~> (open-aoc-input (find-session) 2023 3 #:cache #true) make-board)) - -(define (posn<? a b) - (match-define (list (cons (posn a-x a-y) _) (cons (posn b-x b-y) _)) (list a b)) - (if (= a-y b-y) (< a-x b-x) (< a-y b-y))) - -(define (find-cells f b) - (~> (for/hash ([(k v) (in-hash b)] #:when (f v)) - (values k v)) - hash->list - (sort posn<?))) - -(define (group-into-parts cells [acc '()]) - (match* (cells acc) - [('() acc) - acc] - [((list* (cons (and pt (posn x y)) n) cs) - (list* (part n* (and pts (list* (posn x* y) rest-pts))) - rest-acc)) - #:when (= (- x x*) 1) - (group-into-parts cs (cons (part (+ n (* n* 10)) (cons pt pts)) rest-acc))] - [((list* (cons pt n) cs) acc) - (group-into-parts cs (cons (part n (list pt)) acc))])) - -(define (neighbors p) - (for*/list ([dx '(-1 0 1)] - [dy '(-1 0 1)] - #:unless (and (= dx 0) (= dy 0))) - (posn (+ dx (posn-x p)) (+ dy (posn-y p))))) - -(define to-neighbors (λ~>> part-posns (append-map neighbors) remove-duplicates)) -(define (symbol-in-neighbors b pt acc) - (~>> pt - to-neighbors - (ormap (λ (p) (let ([lookup (hash-ref b p #f)]) - (or (equal? lookup 'gear) (equal? lookup 'other))))) - ((λ (bool) (if bool (+ acc (part-n pt)) acc))))) - -;; part 1 -(define parts (~>> board (find-cells integer?) group-into-parts)) -(foldl (curry symbol-in-neighbors board) 0 parts) - -;; part 2 -(define gears (~>> board (find-cells (curry equal? 'gear)) (map car))) -(define parts-with-neighbors (map (λ (pt) (struct-copy part pt [posns (to-neighbors pt)])) parts)) - -(define (find-parts-near-gear pts gear) - (filter-map (λ (pt) (and (findf (curry equal? gear) (part-posns pt)) (part-n pt))) pts)) - -(~>> gears - (filter-map (λ~>> (find-parts-near-gear parts-with-neighbors) - ((λ (ns) (if (= (length ns) 2) (* (first ns) (second ns)) #f))))) - (apply +)) |