221 lines
7.3 KiB
Scheme
221 lines
7.3 KiB
Scheme
;; The Computer Language Benchmarks Game
|
|
;; http://shootout.alioth.debian.org/
|
|
;;
|
|
;; Based on a Python version:
|
|
;; contributed by Olof Kraigher
|
|
;; modified by Tupteq
|
|
;; contributed by Matthew Flatt
|
|
;; optimized by Eli Barzilay
|
|
|
|
#lang scheme/base
|
|
(require scheme/cmdline scheme/list)
|
|
|
|
(define width 5)
|
|
(define height 10)
|
|
(define size (* width height))
|
|
|
|
(define (valid-xy? x y)
|
|
(and (0 . <= . x)
|
|
(x . < . width)
|
|
(0 . <= . y)
|
|
(y . < . height)))
|
|
|
|
(define (mover fun)
|
|
(let ([t (make-vector size)])
|
|
(for ([p (in-range size)])
|
|
(vector-set! t p (let*-values ([(y x) (quotient/remainder p width)]
|
|
[(x y) (fun x y)])
|
|
(if (valid-xy? x y) (+ x (* y width)) -1))))
|
|
t))
|
|
|
|
(define E
|
|
(mover (lambda (x y) (values (add1 x) y))))
|
|
(define W
|
|
(mover (lambda (x y) (values (sub1 x) y))))
|
|
(define NE
|
|
(mover (lambda (x y) (values (+ x (bitwise-and y 1)) (sub1 y)))))
|
|
(define NW
|
|
(mover (lambda (x y) (values (sub1 (+ x (bitwise-and y 1))) (sub1 y)))))
|
|
(define SE
|
|
(mover (lambda (x y) (values (+ x (bitwise-and y 1)) (add1 y)))))
|
|
(define SW
|
|
(mover (lambda (x y) (values (sub1 (+ x (bitwise-and y 1))) (add1 y)))))
|
|
|
|
(define rotate-list (list E NE NW W SW SE E))
|
|
(define (rotate dir)
|
|
(cadr (memq dir rotate-list)))
|
|
|
|
(define flip-alist (list (cons E W) (cons NE NW) (cons NW NE)
|
|
(cons W E) (cons SW SE) (cons SE SW)))
|
|
(define (flip dir) (cdr (assq dir flip-alist)))
|
|
|
|
(define movers (list E W NE NW SE SW))
|
|
|
|
(define (valid? p)
|
|
(p . >= . 0))
|
|
|
|
(define (clear? board pos)
|
|
(not (bitwise-bit-set? board pos)))
|
|
(define (set board pos)
|
|
(bitwise-ior board (arithmetic-shift 1 pos)))
|
|
|
|
(define (zero-count board)
|
|
(for/fold ([count 0]) ([i (in-range size)])
|
|
(if (clear? board i) (add1 count) count)))
|
|
|
|
(define (find-free-cell board)
|
|
(for/or ([p (in-range 0 size)])
|
|
(and (clear? board p) p)))
|
|
|
|
(define (flood-fill board p)
|
|
(for/fold ([board (set board p)]) ([mover (in-list movers)])
|
|
(let ([p (vector-ref mover p)])
|
|
(if (and (valid? p) (clear? board p))
|
|
(flood-fill board p)
|
|
board))))
|
|
|
|
(define (no-islands? mask)
|
|
(let ([zeros (zero-count mask)])
|
|
(and (zeros . >= . 5)
|
|
(let loop ([mask mask] [zeros zeros])
|
|
(if (= mask #x3FFFFFFFFFFFF)
|
|
#t
|
|
(let* ([p (find-free-cell mask)]
|
|
[mask (flood-fill mask p)]
|
|
[new-zeros (zero-count mask)])
|
|
(and ((- zeros new-zeros) . >= . 5)
|
|
(loop mask new-zeros))))))))
|
|
|
|
(define (get-bitmask p piece)
|
|
(let ([mask (arithmetic-shift 1 p)])
|
|
(let loop ([p p] [cells piece] [mask mask])
|
|
(if (null? cells)
|
|
mask
|
|
(let ([p (vector-ref (car cells) p)])
|
|
(and (valid? p) (loop p (cdr cells) (set mask p))))))))
|
|
|
|
(define (all-bitmasks piece color)
|
|
(let ([pieces
|
|
(let-values ([(accum piece)
|
|
(for/fold ([accum null] [piece piece])
|
|
([orientations (in-range 2)])
|
|
(let-values ([(accum piece)
|
|
(for/fold ([accum accum] [piece piece])
|
|
([orientations (in-range (- 6 (* 3 (if (= color 4) 1 0))))])
|
|
(values (cons piece accum)
|
|
(map rotate piece)))])
|
|
(values accum (map flip piece))))])
|
|
accum)])
|
|
(reverse
|
|
(for*/fold ([accum null])
|
|
([piece (in-list pieces)]
|
|
[p (in-range 0 size)])
|
|
(let ([mask (get-bitmask p piece)])
|
|
(if (and mask (no-islands? mask)) (cons mask accum) accum))))))
|
|
|
|
(define generate-bitmasks-pieces
|
|
(list (list E E E SE)
|
|
(list SE SW W SW)
|
|
(list W W SW SE)
|
|
(list E E SW SE)
|
|
(list NW W NW SE SW)
|
|
(list E E NE W)
|
|
(list NW NE NE W)
|
|
(list NE SE E NE)
|
|
(list SE SE E SE)
|
|
(list E NW NW NW)))
|
|
(define (generate-bitmasks)
|
|
(let ([masks-at-cell
|
|
(list->vector
|
|
(for/list ([i (in-range size)])
|
|
(list->vector (for/list ([j (in-range 10)]) null))))])
|
|
(for ([piece (in-list generate-bitmasks-pieces)]
|
|
[color (in-naturals)])
|
|
(let loop ([masks (sort (all-bitmasks piece color) >)]
|
|
[cell-bit (sub1 size)]
|
|
[cell-counter (sub1 size)])
|
|
(if (null? masks)
|
|
masks-at-cell
|
|
(if (bitwise-bit-set? (car masks) cell-bit)
|
|
(let ([vec (vector-ref masks-at-cell cell-counter)])
|
|
(vector-set! vec color (cons (car masks) (vector-ref vec color)))
|
|
(loop (cdr masks) cell-bit cell-counter))
|
|
(loop masks (sub1 cell-bit) (sub1 cell-counter))))))
|
|
(for ([v (in-vector masks-at-cell)])
|
|
(for ([j (in-naturals)]
|
|
[val (in-vector v)])
|
|
(vector-set! v j (reverse val))))
|
|
masks-at-cell))
|
|
|
|
(define masks-at-cell (generate-bitmasks))
|
|
|
|
(define masks (make-vector 10 0))
|
|
(define to-go 0)
|
|
(define solutions (mcons #f #f)) ; keeps (min max) solutions
|
|
|
|
(define (solve-cell! cell board)
|
|
(when (and (positive? to-go) (not (negative? cell)))
|
|
;; Need solutions and not off board
|
|
(cond [(= board #x3FFFFFFFFFFFF)
|
|
;; Solved
|
|
(add-solutions!)]
|
|
[(not (clear? board cell))
|
|
;; Cell full, so try next
|
|
(solve-cell! (sub1 cell) board)]
|
|
[else
|
|
;; Recur
|
|
(for* ([color (in-range 10)]
|
|
#:when (zero? (vector-ref masks color))
|
|
[mask (in-list (vector-ref (vector-ref masks-at-cell cell)
|
|
color))]
|
|
#:when (zero? (bitwise-and mask board)))
|
|
(vector-set! masks color mask)
|
|
(solve-cell! (sub1 cell) (bitwise-ior board mask))
|
|
(vector-set! masks color 0))])))
|
|
|
|
(define (add-solutions!)
|
|
(define (add! solution)
|
|
(cond [(not (mcar solutions))
|
|
(set-mcar! solutions solution)
|
|
(set-mcdr! solutions solution)]
|
|
[(bytes<? solution (mcar solutions))
|
|
(set-mcar! solutions solution)]
|
|
[(bytes>? solution (mcdr solutions))
|
|
(set-mcdr! solutions solution)]))
|
|
(let* ([s (list->bytes
|
|
(for/list ([pos (in-range size)])
|
|
(for/or ([color (in-range 10)])
|
|
(and (not (clear? (vector-ref masks color) pos))
|
|
(+ color (char->integer #\0))))))]
|
|
[ns (make-bytes size)])
|
|
;; Inverse
|
|
(for* ([y (in-range height)]
|
|
[x (in-range width)])
|
|
(bytes-set! ns (+ x (* y width))
|
|
(bytes-ref s (+ (- width (+ x 1))
|
|
(* width (- height (+ y 1)))))))
|
|
;; Keep first and last only
|
|
(add! s)
|
|
(add! ns)
|
|
(set! to-go (- to-go 2))))
|
|
|
|
(define (print-solution solution)
|
|
(let ([solution (bytes->string/utf-8 solution)])
|
|
(for ([y (in-range height)])
|
|
(when (odd? y) (display " "))
|
|
(for ([x (in-range width)])
|
|
(printf "~a " (string-ref solution (+ x (* y width)))))
|
|
(printf "\n"))
|
|
(newline)))
|
|
|
|
(define (solve! n)
|
|
(set! to-go n)
|
|
(solve-cell! (sub1 size) 0))
|
|
|
|
(command-line #:args (n)
|
|
(let ([n (string->number n)])
|
|
(solve! n)
|
|
(printf "~a solutions found\n\n" (- n to-go))
|
|
(print-solution (mcar solutions))
|
|
(print-solution (mcdr solutions))))
|