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Diffstat (limited to '2015/day-03/day-03.rkt')
| -rw-r--r-- | 2015/day-03/day-03.rkt | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/2015/day-03/day-03.rkt b/2015/day-03/day-03.rkt new file mode 100644 index 0000000..efa09ad --- /dev/null +++ b/2015/day-03/day-03.rkt @@ -0,0 +1,36 @@ +#lang racket +(require "../../jj-aoc.rkt" + threading + (only-in algorithms chunks-of) + (only-in awesome-list transpose) + racket/hash) + +(define directions + (for/list ([l (in-input-port-chars (open-day 3 2015))]) + (string->symbol (string l)))) + +(define (trace-santa dirs) + (define visits (make-hash)) + (for/fold ([x 0] + [y 0] + #:result visits) + ([dir (in-list dirs)]) + (hash-set! visits `(,x ,y) #true) + (match dir + ['^ (values x (add1 y))] + ['v (values x (sub1 y))] + ['< (values (add1 x) y)] + ['> (values (sub1 x) y)]))) + +;; part 1 +(~> directions trace-santa hash-values length) + +;; part 2 +(~> directions + (chunks-of 2) + transpose + (map trace-santa _) + (match-define (list real robo) _)) + +(hash-union! real robo #:combine (λ _ #true)) +(~> real hash-values length)
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