diff options
Diffstat (limited to '2020/day-16/day-16.rkt')
| -rw-r--r-- | 2020/day-16/day-16.rkt | 36 |
1 files changed, 27 insertions, 9 deletions
diff --git a/2020/day-16/day-16.rkt b/2020/day-16/day-16.rkt index 64271c7..9a38eda 100644 --- a/2020/day-16/day-16.rkt +++ b/2020/day-16/day-16.rkt @@ -1,6 +1,8 @@ #lang racket -(require advent-of-code +(require racket/struct + advent-of-code + fancy-app relation threading rebellion/base/range) @@ -22,13 +24,29 @@ (match-define (list (app (λ~>> make-lines (map process-rules)) ticket-rules) (app (λ~>> make-lines second seperate-fields) your-ticket) (app (λ~>> make-lines rest (map seperate-fields)) other-tickets)) - (~> (fetch-aoc-input (find-session) 2020 16) (string-split "\n\n"))) + (~> (fetch-aoc-input (find-session) 2020 16 #:cache #true) (string-split "\n\n"))) -(define (ticket-scanning-error-rate ticket rules) - (for/sum ([ticket-field (in-list ticket)] - [ticket-rule (in-list rules)] - #:do [(match-define (field-rule _ r1 r2) ticket-rule)] - #:unless (or (range-contains? r1 ticket-field) (range-contains? r2 ticket-field))) - ticket-field)) +;; part 1 +(define (fails-all-checks? field rules) + (define rule-list (~>> rules (map (λ~> struct->list rest)) flatten)) + (for/and ([rule (in-list rule-list)]) + (not (range-contains? rule field)))) -(for/sum ([ticket (in-list other-tickets)]) (ticket-scanning-error-rate ticket ticket-rules))
\ No newline at end of file +(define (ticket-scanning-error-rate tickets rules) + (for*/sum + ([ticket (in-list tickets)] (field (in-list ticket)) #:when (fails-all-checks? field rules)) + field)) + +(ticket-scanning-error-rate other-tickets ticket-rules) + +;; part 2 +(define valid-tickets (filter (ormap (fails-all-checks? _ ticket-rules) _) other-tickets)) + +(define fields (apply map list valid-tickets)) + +(for/list ([field (in-list fields)]) + (for*/list ( + [rule (in-list ticket-rules)] + #:unless (not (or (range-contains? (field-rule-range1 rule) value) + (range-contains? (field-rule-range2 rule) value)))) + (field-rule-name rule))) |