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#!/usr/bin/env perl
# vim:set ts=4 sw=4 sts=4 et ai wm=0 nu:
#=============================================================================
# Copyright (c) 2025, Bob Lied
#=============================================================================
# ch-1.pl Perl Weekly Challenge 340 Task 1 Duplicate Removals
#=============================================================================
# You are given a string, $str, consisting of lowercase English letters.
# Write a script to return the final string after all duplicate removals
# have been made. Repeat duplicate removals on the given string until we
# no longer can. A duplicate removal consists of choosing two adjacent
# and equal letters and removing them.
#
# Example 1 Input: $str = 'abbaca'
# Output: 'ca'
# Step 1: Remove 'bb' => 'aaca'
# Step 2: Remove 'aa' => 'ca'
# Example 2 Input: $str = 'azxxzy'
# Output: 'ay'
# Example 3 Input: $str = 'aaaaaaaa'
# Output: ''
# Example 4 Input: $str = 'aabccba'
# Output: 'a'
# Example 5 Input: $str = 'abcddcba'
# Output: ''
#=============================================================================
use v5.42;
use Getopt::Long;
my $Verbose = false;
my $DoTest = false;
GetOptions("test" => \$DoTest, "verbose" => \$Verbose);
#=============================================================================
exit(!runTest()) if $DoTest;
say dupRmv($_) for @ARGV;
#=============================================================================
sub dupRmv($str)
{
while ( $str =~ s/(.)\1//g ) { }
return $str;
}
sub runTest
{
use Test2::V0;
is( dupRmv('abbaca'), 'ca', "Example 1");
is( dupRmv('azxxzy'), 'ay', "Example 2");
is( dupRmv('aaaaaaaa'), '', "Example 3");
is( dupRmv('aabccba'), 'a', "Example 4");
is( dupRmv('abcddcba'), '', "Example 5");
done_testing;
}
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