in reply to Longest possible run of a single character

TIMTOWTDI. You can also get the positions of the "borders", i.e. places where the character sequences change: 
#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

my $s = 'ABDBACCBBBCBDDBCDCBCCDBABCBABBBBBADACDABAC';
my $p = 0;
my $max = 0;

while ($s =~ /(?<=(.))(?!\1)/g) {
    my $l = pos($s) - $p;
    $max = $l if $l > $max;
    $p = pos $s;
}
say $max;

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Re^2: Longest possible run of a single character
by Anonymous Monk on Sep 24, 2015 at 21:46 UTC

    EXTREME TIMTOWTDI :) 

    #!/usr/bin/perl -l

# http://perlmonks.org/?node_id=551038

use strict;
use warnings;

$_ = 'ABDBACCBBBCBDDBCDCBCCDBABCBABBBBBADACDABACC';

print "longest run: ", length eval "'".s/(.)\K\B(?!\1)/'|'/gr."'";

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[d/l]

      EXTREME TIMTOWTDI the other way around :) 

      #!/usr/bin/perl -l

# http://perlmonks.org/?node_id=551038

use strict;
use warnings;

$_ = 'ABDBACCBBBCBDDBCDCBCCDBABCBABBBBBADACDABACC';

print "longest run: ", length eval "'".s/(.)\1*\K/'|'/gr."'";

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[d/l]

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