You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
34 lines
1.2 KiB
Racket
34 lines
1.2 KiB
Racket
#lang br
|
|
(require racket/file rackunit racket/set graph)
|
|
|
|
(define str (file->string "20.rktd"))
|
|
|
|
(define (find-cells pred)
|
|
(for*/hasheqv ([(row ridx) (in-indexed (string-split str "\n"))]
|
|
[(c cidx) (in-indexed row)]
|
|
#:when (pred c))
|
|
(values (make-rectangular cidx ridx) c)))
|
|
|
|
(define passage-locs (find-cells (λ (c) (char=? c #\.))))
|
|
(define letter-locs (find-cells char-alphabetic?))
|
|
|
|
(define g (unweighted-graph/undirected null))
|
|
|
|
(for* ([loc (in-hash-keys passage-locs)]
|
|
[delta (list 1 -1 +i -i)])
|
|
(when (hash-has-key? passage-locs (+ loc delta))
|
|
(add-edge! g loc (+ loc delta)))
|
|
(when (hash-has-key? letter-locs (+ loc delta))
|
|
(add-edge! g loc (string->symbol
|
|
(apply string ((if (member delta (list -1 -i))
|
|
reverse
|
|
values) (for/list ([d (list delta (* 2 delta))])
|
|
(hash-ref letter-locs (+ loc d)))))))))
|
|
|
|
(for ([v (in-vertices g)]
|
|
#:when (and (symbol? v) (not (memq v '(AA ZZ)))))
|
|
(apply add-edge! g (get-neighbors g v)))
|
|
|
|
|
|
;; 1
|
|
(check-eq? (- (length (fewest-vertices-path g 'AA 'ZZ)) 3) 638) |