35 lines
909 B
Perl
35 lines
909 B
Perl
use strict;
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use warnings;
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use feature 'say';
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use List::Util 'min';
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use ntheory 'is_prime';
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sub rotate { my($i,@a) = @_; join '', @a[$i .. @a-1, 0 .. $i-1] }
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sub isCircular {
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my ($n) = @_;
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return 0 unless is_prime($n);
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my @circular = split //, $n;
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return 0 if min(@circular) < $circular[0];
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for (1 .. scalar @circular) {
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my $r = join '', rotate($_,@circular);
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return 0 unless is_prime($r) and $r >= $n;
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}
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1
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}
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say "The first 19 circular primes are:";
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for ( my $i = 1, my $count = 0; $count < 19; $i++ ) {
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++$count and print "$i " if isCircular($i);
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}
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say "\n\nThe next 4 circular primes, in repunit format, are:";
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for ( my $i = 7, my $count = 0; $count < 4; $i++ ) {
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++$count and say "R($i)" if is_prime 1 x $i
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}
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say "\nRepunit testing:";
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for (5003, 9887, 15073, 25031, 35317, 49081) {
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say "R($_): Prime? " . (is_prime 1 x $_ ? 'True' : 'False');
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}
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