Rep-string: Difference between revisions

=={{header|Perl 6}}==

<lang perl6>for <1001110011 1110111011 0010010010 1010101010 1111111111 0100101101 0100100 101 11 00 1> {

if /^ (.+) $0+: (.*$) <?{ $0.substr(0,$1.chars) eq $1 }> / {

my $rep = $0.chars;

say .substr(0,$rep), .substr($rep,$rep).trans('01' => '𝟘𝟙'), .substr($rep*2);

}

else {

say "$_ (no repeat)";

}

}</lang>

{{out}}

<pre>10011𝟙𝟘𝟘𝟙𝟙

1110𝟙𝟙𝟙𝟘11

001𝟘𝟘𝟙0010

1010𝟙𝟘𝟙𝟘10

11111𝟙𝟙𝟙𝟙𝟙

0100101101 (no repeat)

010𝟘𝟙𝟘0

101 (no repeat)

1𝟙

0𝟘

1 (no repeat)</pre>

Here's a technique that relies on the fact that XORing the shifted binary number

should set all the lower bits to 0 if there are repeats.

(The cool thing is that shift will automatically

throw away the bits on the right that you want thrown away.)

This produces the same output as above.

<lang perl6>sub repstr(Str $s) {

my $bits = :2($s);

for reverse 1 .. $s.chars div 2 -> $left {

my $right = $s.chars - $left;

return $left if $bits +^ ($bits +> $left) == $bits +> $right +< $right;

}

}

for '1001110011 1110111011 0010010010 1010101010 1111111111 0100101101 0100100 101 11 00 1'.words {

if repstr $_ -> $rep {

say .substr(0,$rep), .substr($rep,$rep).trans('01' => '𝟘𝟙'), .substr($rep*2);

}

else {

say "$_ (no repeat)";

}

}</lang>