master
Matthew Butterick 6 years ago
parent bf76aeb6fe
commit c9f3bcb6c8

@ -0,0 +1 @@
dabAcCaCBAcCcaDA

@ -0,0 +1,41 @@
#lang debug br
(require racket/file racket/set)
(define fp (open-input-file "05.txt"))
(define fpbs (port->bytes fp))
(define (react fpbs)
(let/ec exit
(for/fold ([bs fpbs])
([i (in-naturals)])
(or
(for/first ([(left lidx) (in-indexed bs)]
[right (in-bytes (subbytes bs 1))]
#:when (= 32 (abs (- left right))))
(bytes-append (subbytes bs 0 lidx) (subbytes bs (+ lidx 2))))
(exit (bytes-length bs))))))
(define ()
(react fpbs))
(define possible-units
(map char->integer (remove-duplicates (map char-upcase (map integer->char (bytes->list fpbs))) char=?)))
(define (remove-unit fbps unit)
(apply bytes
(for/list ([b (in-bytes fbps)]
#:unless (or (= b unit)
(= b (+ unit 32))))
b)))
;; very slow.
(define (★★)
(argmin cdr
(for/list ([(unit idx) (in-indexed possible-units)])
(cons unit (react (remove-unit fpbs unit))))))
(module+ test
(require rackunit)
(check-equal? (time ()) 10564)
(check-equal? (time (★★)) 6336))

File diff suppressed because one or more lines are too long