diff options
Diffstat (limited to 'aoc2023-other/day-23/day-23.rkt')
| -rw-r--r-- | aoc2023-other/day-23/day-23.rkt | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/aoc2023-other/day-23/day-23.rkt b/aoc2023-other/day-23/day-23.rkt index 3840187..c048013 100644 --- a/aoc2023-other/day-23/day-23.rkt +++ b/aoc2023-other/day-23/day-23.rkt @@ -10,7 +10,7 @@ [(col c) (in-indexed row)] #:when (not (equal? col #\#))) ; for now, we don't actually need to detect paths and slopes, just not-rocks - ; in part 1, all forks in the road go left or down, so we can just infer the path + ; in part 1, all forks in the road go right or down, so we can just infer the path ; direction from the shape of the junction and form a network of junctions from there ; in part 2, the slopes are removed anyway (values (cons (add1 r) (add1 c)) col))) @@ -23,7 +23,8 @@ (define (get-neighbors posn type) (match-define (cons r c) posn) (match type - ['junction (~> (set (cons (add1 r) c) (cons r (add1 c))))] + ['junction + (~> (set (cons (add1 r) c) (cons r (add1 c))))] [_ (~> (list (cons (add1 r) c) (cons (sub1 r) c) (cons r (add1 c)) (cons r (sub1 c))) (filter (curry hash-has-key? trails) _) @@ -41,7 +42,9 @@ [else (values k 'trail)]))) (define (walk-to-next-junction start current [length 1] [seen (set start)]) - (define next (~> current (get-neighbors _ 'trail) (set-subtract seen) set-first)) + (define next (~> current + (get-neighbors _ 'trail) + (set-subtract seen) set-first)) (cond [(equal? (hash-ref trails-with-junctions next) 'junction) (list (- (add1 length)) start next)] ; weird format is due to graph library @@ -77,7 +80,7 @@ [(equal? from to) acc] [else (define choices (filter (λ (path) (not (set-member? seen (car path)))) (hash-ref g from))) - (if (empty? choices) 0 ;; long dead-ends don't count + (if (empty? choices) 0 ; long dead-ends don't count (for/fold ([best acc]) ([path (in-list choices)] #:do [(match-define (cons next dist) path)]) |