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#lang racket
(require "../../jj-aoc.rkt"
threading)
(struct instruction (todo x1 y1 x2 y2) #:transparent)
(define (make-instruction lst)
(apply instruction (string->symbol (first lst)) (map string->number (rest lst))))
(define instructions
(for/list ([l (in-lines (open-day 6 2015))])
(~>> l
(regexp-match
#px"(turn on|toggle|turn off) (\\d{1,3}),(\\d{1,3}) through (\\d{1,3}),(\\d{1,3})")
rest
make-instruction)))
(define (vector2d-modify! vec x y f)
(define pos (+ x (* 1000 y)))
(vector-set! vec pos (f (vector-ref vec pos))))
;; part 1
(define (todo inst)
(match (instruction-todo inst)
['|turn on| (λ _ #true)]
['|turn off| (λ _ #false)]
['|toggle| not]))
(define (modify-light-grid inst light-grid using)
(for ([x (inclusive-range (instruction-x1 inst) (instruction-x2 inst))])
(for ([y (inclusive-range (instruction-y1 inst) (instruction-y2 inst))])
(vector2d-modify! light-grid x y (using inst)))))
(define light-grid (make-vector (* 1000 1000) #false))
(for ([i (in-list instructions)])
(modify-light-grid i light-grid todo))
(vector-count identity light-grid)
;; part 2
(define (todo-dimmer inst)
(match (instruction-todo inst)
['|turn on| add1]
['|turn off| (λ (x) (max 0 (sub1 x)))]
['|toggle| (curry + 2)]))
(define dimmable-grid (make-vector (* 1000 1000) 0))
(for ([i (in-list instructions)])
(modify-light-grid i dimmable-grid todo-dimmer))
(apply + (vector->list dimmable-grid))
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