Hello.

I was trying to solve a problem about UTF-8, and went with solution which is too slow. I want to ask suggestions how to optimize my code, or suggestions about better approaches. Maybe with using pack/unpack, but I've found perlpacktut not very clear for me.

I have no idea how to write a problem statement from .pdf paper, so I made some screenshots.
How would you solve this problem?

Test case #1: 
C1 B3 E0 81 B3 F0 80 81 B3
F8 80 80 81 B3 FC 80 80 80
81 B3 80 C1 B3 E0 81 B3 F0
80 81 B3 F8 80 80 81 B3 FC 80
80 80 81 B3 E0 AF B5

[download]
Test case #2: 
FF 00 FF D1 81 F0 80 91 81
00 D1 81 FF F0 80 91 81 FF
FF 00 D1 81 F0 80 91 81

[download]
Output for TC #1: 
73 73 73 73 73
73 73 73 73 73 BF5

[download]
Output for TC #2: 
441 441 0 441
0 441 441

[download]
My code which solves two tests correctly, but it is slow for bigger tests (can't see them), and maybe it is incorrect(?): 
#!/usr/bin/perl

use warnings;
use strict;

$\ = $/;
my $debug = 0;

$_ = do { local $/; <> };

@_ = split;

$_ = join '', map { sprintf "%08b", eval "0x$_" } @_, 'FF';

my @data = reverse <DATA>;
chomp @data;

y/x/./ for @data;

my @rxs = join '|', @data;

my @r;
my @R;

while( /\G(?:@rxs|.{8})/g ){
    my $c = $&;
    $debug and print "c:$c";
    
    $c =~ /@rxs/ or do {
        push @R, [ @r ] if @r > 2;
        @r = ();
        $debug and print "   -F";
        next;
        };
    
    my $x = $c =~ s/.{8}/ ($&) =~ s!^1+0!!r /ger;
    $debug and print "x:",$x;
    
    push @r, ~~ reverse $x;
    }

my @acc;
my @ACC;

for my $R (@R){
    
    @acc = ();
    for my $r ( @{ $R } ){
        
        my $acc = '';
        
        while( $r =~ /.{1,4}/g ){
            $acc .= ( 0 .. 9, 'A' .. 'F' )[ eval "0b" . reverse $& ];
            }
        
        $acc = reverse $acc;
        $acc =~ s/^0+\B//;
        
        push @acc, $acc;
        }
        
    push @ACC, "@acc";
}

print for @ACC;

__DATA__
0xxxxxxx
110xxxxx10xxxxxx
1110xxxx10xxxxxx10xxxxxx
11110xxx10xxxxxx10xxxxxx10xxxxxx
111110xx10xxxxxx10xxxxxx10xxxxxx10xxxxxx
1111110x10xxxxxx10xxxxxx10xxxxxx10xxxxxx10xxxxxx

[download]

In reply to contest problem about UTF-8 by rsFalse

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