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aoc-racket
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in-slice

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master
Matthew Butterick 7 years ago
parent 11ee809772
commit 6114504d73
1 changed files with 3 additions and 4 deletions
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7
2017/d10/main.rkt
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@ -1,5 +1,5 @@
#lang br/quicklang #lang br/quicklang
(require "../helper.rkt") (require "../helper.rkt" racket/sequence)
(provide read-syntax (rename-out [#%mb #%module-begin])) (provide read-syntax (rename-out [#%mb #%module-begin]))
(define (read-syntax path port) (define (read-syntax path port)
@ -26,9 +26,8 @@
(define (two-star str) (define (two-star str)
(define ascii-chars (map char->integer (string->list str))) (define ascii-chars (map char->integer (string->list str)))
(reverse-segments (append ascii-chars '(17 31 73 47 23)) #:count 64) (reverse-segments (append ascii-chars '(17 31 73 47 23)) #:count 64)
(define dense-hash (for/list ([i (in-range 16)]) (define dense-hash (for/list ([vals (in-slice 16 (vector->list vec))])
(apply bitwise-xor (for/list ([v (in-vector vec (* i 16) (* (add1 i) 16))]) (apply bitwise-xor vals)))
v))))
(string-append* (for/list ([num (in-list dense-hash)]) (string-append* (for/list ([num (in-list dense-hash)])
(~r num #:base 16 #:min-width 2 #:pad-string "0")))) (~r num #:base 16 #:min-width 2 #:pad-string "0"))))