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  1. #!/usr/bin/env perl
  2. use 5.010;
  3. use strict;
  4. use warnings;
  5.  
  6. my @tests =
  7.   ( "", "( )", "{ ( { ( ) } ( ) ) } ( )", "} {", "( { ) }", "{ } ( { } )", );
  8. my $lefts      = qr< [{(] >x;
  9. my $rights     = qr< [)}] >x;
  10. my %pair_for = (
  11.     ')' => '(',
  12.     '}' => '{',
  13. );
  14.  
  15. my ( $twin, $i, $err, $max_so_far );
  16. $twin = qr{
  17.             (?> [^(){}]* )
  18.             ($lefts)
  19.             (?{$max_so_far = $i if $max_so_far < ++$i})
  20.             (?:
  21.                 (?> [^(){}]+ )
  22.             |
  23.                 (??{$twin})
  24.             )*
  25.             ($rights)
  26.             (?{--$i})
  27.             (?{ unless ($1 eq $pair_for{$2}){++$err} })
  28. }x;
  29.  
  30. for my $test (@tests) {
  31.     ( $i, $err, $max_so_far ) = ( 0, 0, 0 );
  32.     print q("), $test, q("), q( => );
  33.     say 0 and next unless $test;
  34.     ( $test =~ / $twin+ /xg and $err == 0 ) ? say "$max_so_far"
  35.                                             : say -1
  36.                                             ;
  37. }
Success #stdin #stdout 0s 5404KB
comments (?)
stdin
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Standard input is empty
stdout
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"" => 0
"( )" => 1
"{ ( { ( ) } ( ) ) } ( )" => 4
"} {" => -1
"( { ) }" => -1
"{ } ( { } )" => 2
https://ideone.com/1qwl1U
language:
Perl (perl 5.28.1)
created:
5 years ago
visibility:
public

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