You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
95 lines
3.4 KiB
Racket
95 lines
3.4 KiB
Racket
#lang typed/racket
|
|
(require typed/rackunit)
|
|
(provide (all-defined-out))
|
|
(require/typed racket/vector ;;bg; not sure how to express "a pattern, repeating"
|
|
(vector-set*! (All (A) (-> (Vectorof A) Integer A Integer A Integer A Integer A Void))))
|
|
|
|
(define grid-side 102)
|
|
|
|
(: rowcol->idx (-> Integer Integer Integer))
|
|
(define (rowcol->idx row col) (+ (* grid-side row) col))
|
|
|
|
(: idx->rowcol (-> Integer (Values Integer Integer)))
|
|
(define (idx->rowcol idx) (quotient/remainder idx grid-side))
|
|
|
|
(: count-lit (-> (Vectorof Integer) Integer))
|
|
(define (count-lit grid) (apply + (vector->list grid)))
|
|
|
|
(define bulb-on 1)
|
|
(define bulb-off 0)
|
|
|
|
(: input->grid (-> String (Vectorof Integer)))
|
|
(define (input->grid str)
|
|
(define grid-vec : (Vectorof Integer) (make-vector (* grid-side grid-side) bulb-off))
|
|
(for* ([(bulb-row bulb-row-idx) (in-indexed (string-split str))]
|
|
[(bulb bulb-col-idx) (in-indexed (regexp-match* #rx"." bulb-row))])
|
|
(vector-set! grid-vec (rowcol->idx (add1 bulb-row-idx) (add1 bulb-col-idx))
|
|
(if (equal? bulb "#") bulb-on bulb-off)))
|
|
grid-vec)
|
|
|
|
(: bulb+adjacents (-> (Vectorof Integer) Integer (Vectorof Integer)))
|
|
(define (bulb+adjacents grid grid-idx)
|
|
(define-values (row col) (idx->rowcol grid-idx))
|
|
(for*/vector ([r (in-range (sub1 row) (+ row 2))]
|
|
[c (in-range (sub1 col) (+ col 2))])
|
|
: Integer
|
|
(vector-ref grid (rowcol->idx r c))))
|
|
|
|
(: iterate-grid (-> (Vectorof Integer) (Vectorof Integer)))
|
|
(define (iterate-grid grid)
|
|
(for*/vector ([row (in-range grid-side)]
|
|
[col (in-range grid-side)])
|
|
: Integer
|
|
(cond
|
|
[(or (= row 0) (= col 0)
|
|
(= row (sub1 grid-side))
|
|
(= col (sub1 grid-side)))
|
|
bulb-off]
|
|
[else
|
|
(define bulb-idx (rowcol->idx row col))
|
|
(define bulb (vector-ref grid bulb-idx))
|
|
(define lit-neighbors
|
|
(- (count-lit (bulb+adjacents grid bulb-idx)) bulb))
|
|
(cond
|
|
[(= bulb-on bulb) (if (<= 2 lit-neighbors 3) bulb-on bulb-off)]
|
|
[(= 3 lit-neighbors) bulb-on]
|
|
[else bulb-off])])))
|
|
|
|
(: q1 (-> String Integer))
|
|
(define (q1 input-str)
|
|
(define initial-grid (input->grid input-str))
|
|
(define iterations 100)
|
|
(define final-grid (for/fold : (Vectorof Integer)
|
|
([grid-so-far : (Vectorof Integer) initial-grid])
|
|
([i (in-range iterations)])
|
|
(iterate-grid grid-so-far)))
|
|
(count-lit final-grid))
|
|
|
|
|
|
|
|
(: light-corners (-> (Vectorof Integer) (Vectorof Integer)))
|
|
(define (light-corners grid)
|
|
(vector-set*! grid
|
|
(rowcol->idx 1 1) bulb-on
|
|
(rowcol->idx 1 100) bulb-on
|
|
(rowcol->idx 100 1) bulb-on
|
|
(rowcol->idx 100 100) bulb-on)
|
|
grid)
|
|
|
|
(: q2 (-> String Integer))
|
|
(define (q2 input-str)
|
|
(define initial-grid (light-corners (input->grid input-str)))
|
|
(define iterations 100)
|
|
(define final-grid (for/fold : (Vectorof Integer)
|
|
([grid-so-far initial-grid])
|
|
([i (in-range iterations)])
|
|
(light-corners (iterate-grid grid-so-far))))
|
|
(count-lit final-grid))
|
|
|
|
(module+ test
|
|
(define input-str (file->string "../day18-input.txt"))
|
|
(check-equal? (q1 input-str) 821)
|
|
(check-equal? (q2 input-str) 886))
|
|
|
|
|