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aoc-racket
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2016
Matthew Butterick 7 years ago
parent e39fa81687
commit 1d1c9d323b
1 changed files with 16 additions and 16 deletions
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32
2016/day13/lang.rkt
Unescape Escape View File

@ -17,23 +17,23 @@
(define (solve dim num)
(define open? (make-open-pred num))
(define g (undirected-graph '((0 0))))
(for* ([x (in-range dim)]
[y (in-range dim)]
#:when (open? (list y x)))
(when (open? (list (add1 y) x))
(add-edge! g (list y x) (list (add1 y) x)))
(when (open? (list y (add1 x)))
(add-edge! g (list y x) (list y (add1 x)))))
(define path (fewest-vertices-path g '(1 1) '(31 39)))
(for* ([y (in-range dim)]
[x (in-range dim)]
#:when (open? (cons x y)))
(when (open? (cons (add1 x) y))
(add-edge! g (cons x y) (cons (add1 x) y)))
(when (open? (cons x (add1 y)))
(add-edge! g (cons x y) (cons x (add1 y)))))
(define path (fewest-vertices-path g '(1 . 1) '(31 . 39)))
(displayln (and path (sub1 (length path)))))
(define (solve2 num)
(define open? (make-open-pred num))
(define (nonnegative? pt) (and (not (negative? (car pt)))
(not (negative? (cadr pt)))
(not (negative? (cdr pt)))
pt))
(let loop ([all-visited-pts empty]
[last-visited-pts '((1 1))]
[last-visited-pts '((1 . 1))]
[step 0])
(cond
[(= step 50)
@ -42,11 +42,11 @@
(loop (append last-visited-pts all-visited-pts)
(append*
(for/list ([lvp (in-list last-visited-pts)])
(match-define (list x y) lvp)
(for/list ([pt (in-list (list (list (add1 x) y)
(list x (add1 y))
(list (sub1 x) y)
(list x (sub1 y))))]
(match-define (cons x y) lvp)
(for/list ([pt (in-list (list (cons (add1 x) y)
(cons x (add1 y))
(cons (sub1 x) y)
(cons x (sub1 y))))]
#:when (and (nonnegative? pt)
(open? pt)
(not (member pt all-visited-pts))))
@ -55,7 +55,7 @@
(define (make-open-pred num)
(λ(pt)
(match-define (list x y) pt)
(match-define (cons x y) pt)
(define sum
(+ (* x x) (* 3 x) (* 2 x y) y (* y y) num))
(even?