RosettaCodeData/Task/Fusc-sequence/Perl/fusc-sequence.pl

26 lines
589 B
Perl

use strict;
use warnings;
use feature 'say';
sub comma { reverse ((reverse shift) =~ s/(.{3})/$1,/gr) =~ s/^,//r }
sub stern_diatomic {
my ($p,$q,$i) = (0,1,shift);
while ($i) {
if ($i & 1) { $p += $q; } else { $q += $p; }
$i >>= 1;
}
$p;
}
say "First 61 terms of the Fusc sequence:\n" . join ' ', map { stern_diatomic($_) } 0..60;
say "\nIndex and value for first term longer than any previous:";
my $i = 0;
my $l = -1;
while ($l < 5) {
my $v = stern_diatomic($i);
printf("%15s : %s\n", comma($i), comma($v)) and $l = length $v if length $v > $l;
$i++;
}