28 lines
816 B
Raku
28 lines
816 B
Raku
use List::Util qw(none sum);
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sub gcd { my ($u,$v) = @_; $v ? gcd($v, $u%$v) : abs($u) }
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sub shares_divisors_with { gcd( $_[0], $_[1]) > 1 }
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sub EKG {
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my($n,$limit) = @_;
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my @ekg = (1, $n);
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while (@ekg < $limit) {
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for my $i (2..1e18) {
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next unless none { $_ == $i } @ekg and shares_divisors_with($ekg[-1], $i);
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push(@ekg, $i) and last;
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}
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}
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@ekg;
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}
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sub converge_at {
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my($n1,$n2) = @_;
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my $max = 100;
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my @ekg1 = EKG($n1,$max);
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my @ekg2 = EKG($n2,$max);
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do { return $_+1 if $ekg1[$_] == $ekg2[$_] && sum(@ekg1[0..$_]) == sum(@ekg2[0..$_])} for 2..$max;
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return "(no convergence in $max terms)";
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}
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print "EKG($_): " . join(' ', EKG($_,10)) . "\n" for 2, 5, 7, 9, 10;
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print "EKGs of 5 & 7 converge at term " . converge_at(5, 7) . "\n"
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