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