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Diffstat (limited to '2021/day-04/day-04.rkt')
| -rw-r--r-- | 2021/day-04/day-04.rkt | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/2021/day-04/day-04.rkt b/2021/day-04/day-04.rkt new file mode 100644 index 0000000..fdf1ea1 --- /dev/null +++ b/2021/day-04/day-04.rkt @@ -0,0 +1,62 @@ +#lang racket +(require advent-of-code + threading + (only-in awesome-list transpose) + (only-in algorithms chunks-of)) + +(define data + (for/list ([l (in-lines (open-aoc-input (find-session) 2021 4 #:cache (string->path "./cache")))] + #:unless (equal? l "")) + l)) + +(define call-sheet + (~> data + car + (string-split ",") + (map string->number _))) +(define bingo-cards + (~> data + cdr + (map string-split _) + (map (λ (row) (map string->number row)) _) + (chunks-of 5))) + +(define test-card (first bingo-cards)) + +(define (mark-card card call) + (for/list ([row (in-list card)]) + (for/list ([col (in-list row)]) + (if (eq? col call) 'X col)))) + +(define (check-card card) + (for/or ([row (in-sequences card (transpose card))]) + (equal? row '(X X X X X)))) + +(define (multiply-by-last-call n call) + (match n + ['X 0] + [n (* n call)])) + +(define (evaluate-cards cards calls [check (curry ormap check-card)] [exception not]) + (for/fold ([current-cards cards] + [last-call 0] + #:result (~> current-cards + (findf check-card _) + flatten + (map (λ (n) (multiply-by-last-call n last-call)) _) + (apply + _))) + ([call (in-list calls)]) + #:break (check current-cards) + (values (for/list ([card (in-list current-cards)] + #:unless (exception card)) + (mark-card card call)) + call))) + +;; part 1 +(evaluate-cards bingo-cards call-sheet) +;; part 2 +(evaluate-cards bingo-cards + call-sheet + (λ (cards) (and (= (length cards) 1) + (check-card (first cards)))) + check-card)
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