🎄⌨️ Advent of Code 2018

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Comment:fix backwardity
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Timelines: family | ancestors | descendants | both | day15
Files: files | file ages | folders
SHA3-256: 96ef0187bfad6191904d004fa7f1119574bca46af81a1f9caab297ff6e6db8ea
User & Date: joel on 2019-11-27 19:07:46
Other Links: branch diff | manifest | tags
Context
2019-11-28
16:08
evolution check-in: 722424 user: joel tags: day15
2019-11-27
19:07
fix backwardity check-in: 96ef01 user: joel tags: day15
2019-11-26
23:01
Refine what we got check-in: e94fa4 user: joel tags: day15
Changes
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Modified day15.rkt from [124443] to [266d98].

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                  [else (cons ch lst)])))))

;; Is point p inside grid g? Film at 11
(define (inside-grid? g p)
  (match-define (posn px py) p)
  (and (>= px 0)
       (>= py 0)
       (< px (grid-rows g))
       (< py (grid-cols g))))

;; Get a list of a positions neighboring points, ensuring none are out of bounds
(define (neighbor-coords g pos)
  (match-define (posn x y) pos)
  (filter (curry inside-grid? g)
          (map (lambda (lst) (apply posn lst))
               `((,(- x 1) ,y)
                 (,x ,(+ y 1))
                 (,(+ x 1) ,y)
                 (,x ,(- y 1))))))

;; Get all the EMPTY neighboring points of a given spot OR list of spots.
;; If a (listof posn?) is passed, ensures the returned list does not include
;; any of the original positions.
(define (free-neighbors-at world pos)
  (cond [(posn? pos)
         (~> (neighbor-coords world pos)








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                  [else (cons ch lst)])))))

;; Is point p inside grid g? Film at 11
(define (inside-grid? g p)
  (match-define (posn px py) p)
  (and (>= px 0)
       (>= py 0)
       (< px (grid-cols g))
       (< py (grid-rows g))))

;; Get a list of a positions neighboring points, ensuring none are out of bounds
(define (neighbor-coords g pos)
  (match-define (posn x y) pos)
  (filter (curry inside-grid? g)

          (list (posn (- x 1) y)
                (posn x (+ y 1))
                (posn (+ x 1) y)
                (posn x (- y 1)))))

;; Get all the EMPTY neighboring points of a given spot OR list of spots.
;; If a (listof posn?) is passed, ensures the returned list does not include
;; any of the original positions.
(define (free-neighbors-at world pos)
  (cond [(posn? pos)
         (~> (neighbor-coords world pos)
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