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32 lines
987 B
Racket
32 lines
987 B
Racket
2 years ago
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#lang br
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(require racket/file sugar/list rackunit)
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(define instructions
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(slice-at (for/list ([datum (in-port read (open-input-file "02.rktd"))])
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datum) 2))
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(define (solve matcher)
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(for/fold ([pos 0]
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[depth 0]
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[aim 0]
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#:result (* pos depth))
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([i (in-list instructions)])
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(matcher pos depth aim i)))
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(define (solve-1)
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(solve (λ (pos depth aim i)
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(match i
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[(list 'forward amt) (values (+ pos amt) depth aim)]
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[(list 'down amt) (values pos (+ depth amt) aim)]
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[(list 'up amt) (values pos (- depth amt) aim)]))))
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(check-equal? (solve-1) 1488669)
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(define (solve-2)
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(solve (λ (pos depth aim i)
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(match i
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[(list 'forward amt) (values (+ pos amt) (+ depth (* aim amt)) aim)]
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[(list 'down amt) (values pos depth (+ aim amt))]
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[(list 'up amt) (values pos depth (- aim amt))]))))
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(check-equal? (solve-2) 1176514794)
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