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#!/usr/bin/perl
use v5.26;
use Test2::V0 -no_srand;
use Test2::Tools::Subtest 'subtest_streamed';
use Getopt::Long;
use experimental 'signatures';
### Options and Arguments
my ($tests, $examples, $verbose);
GetOptions(
'examples!' => \$examples,
'tests!' => \$tests,
'verbose!' => \$verbose,
) or usage();
run_tests($examples, $tests); # tests do not return
usage() unless @ARGV == 1;
sub usage {
die <<~EOS;
$0 - odd letters
usage: $0 [-examples] [-tests] [STR]
-examples
run the examples from the challenge
-tests
run some tests
STR
a string
EOS
}
### Input and Output
say +(qw(true false))[!odd_letters(shift)];
### Implementation
#
# For details see:
# https://github.sommrey.de/the-bears-den/2025/08/01/ch-332.html#task-2
sub odd_letters {
shift !~ /
(.)
(?!(?=(.*))(\1.+(?=\g{-2}$)|(?<=(?=x^|(?-1)).)))
((??{qr([^$1]*)})\1)
(?:(?-1){2})*
(?!.*\1)
/x;
}
### Examples and Tests
sub run_tests ($examples, $tests) {
return unless $examples || $tests;
state sub run_example ($args, $expected, $name) {
my $result = odd_letters(@$args);
is $result, $expected,
"$name: (@$args) -> " . $expected->name;
}
plan 2;
$examples ? subtest_streamed(examples => sub {
my @examples = (
[["weekly"], F(), 'example 1'],
[["perl"], T(), 'example 2'],
[["challenge"], F(), 'example 3'],
);
plan scalar @examples;
for (@examples) {
run_example @$_;
}
}) : pass 'skip examples';
$tests ? subtest_streamed(tests => sub {
my @tests = (
[["abccbabac"], T(), 'all multiple'],
[["abccbababc"], F(), 'all multiple, single even'],
);
plan scalar @tests;
for (@tests) {
run_example @$_;
}
}) : pass 'skip tests';
exit;
}
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