14 lines
346 B
Plaintext
14 lines
346 B
Plaintext
(define nums '(1 2 3 4 5 6 7 8 9))
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(define valid
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(lambda (x)
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(foldr
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(lambda (y z)
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(match (filter (lambda (q) (= q y)) nums)
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(((? r) . nil) (match (filter (lambda (q) (= r q)) x)
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(((? _)) z)
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(_ nil)))
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(_ nil)))
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t
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x)))
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