29 lines
770 B
Text
29 lines
770 B
Text
func is_circular_prime(n) {
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n.is_prime || return false
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var circular = n.digits
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circular.min < circular.tail && return false
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for k in (1 ..^ circular.len) {
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with (circular.rotate(k).digits2num) {|p|
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(p.is_prime && (p >= n)) || return false
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}
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}
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return true
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}
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say "The first 19 circular primes are:"
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say 19.by(is_circular_prime)
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say "\nThe next 4 circular primes, in repunit format, are:"
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{|n| (10**n - 1)/9 -> is_prob_prime }.first(4, 4..Inf).each {|n|
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say "R(#{n})"
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}
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say "\nRepunit testing:"
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[5003, 9887, 15073, 25031, 35317, 49081].each {|n|
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var now = Time.micro
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say ("R(#{n}) -> ", is_prob_prime((10**n - 1)/9) ? 'probably prime' : 'composite',
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" (took: #{'%.3f' % Time.micro-now} sec)")
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}
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