30 lines
827 B
Scheme
30 lines
827 B
Scheme
(import (chicken io)
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srfi-1
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srfi-152
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matchable)
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(define (read-input #!optional (port (current-input-port)))
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(map (lambda (s) (let ((l (string-split s " ")))
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(list (string->symbol (car l))
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(string->number (cadr l)))))
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(read-lines port)))
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(define (move steps pos depth aim)
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(match steps
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(() (values pos depth aim))
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((('down n) . rest) (move rest pos depth (+ aim n)))
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((('up n) . rest) (move rest pos depth (- aim n)))
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((('forward n) . rest) (move rest (+ pos n) (+ depth (* aim n)) aim))
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(_ (error "unknown instruction" (car steps)))))
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(define (part1 l)
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(let-values (((pos depth aim) (move l 0 0 0)))
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(* pos aim)))
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(define (part2 l)
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(let-values (((pos depth aim) (move l 0 0 0)))
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(* pos depth)))
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(let ((in (read-input)))
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(print (part1 in))
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(print (part2 in)))
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