blob: c572f740d176332187be518a734a1e78a4a03f5c (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
|
#lang racket
(require advent-of-code
threading
(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 (apply map list 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)
|
