17 lines
544 B
Common Lisp
17 lines
544 B
Common Lisp
(defun prime-sum-count (n primes)
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(let ((primes-descending (reverse primes)))
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(labels ((recurse (primes target)
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(cond ((= target 0) 1)
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((< target 0) 0)
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((null primes) 0)
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(t (+ (recurse primes (- target (first primes)))
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(recurse (rest primes) target))))))
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(recurse primes-descending n))))
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(defun p77 (&key (ways 5000) (prime-count 1000))
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(let ((primes (get-primes prime-count)))
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(loop for n upfrom 1
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for count = (prime-sum-count n primes)
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until (> count ways)
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finally (return n))))
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