#!usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my $num_viol = 'number of violation(s)';

sub extract_data {
    my (@lines) = @_;
    my %hash;
    foreach my $line (@lines) {
	my @tmp = split / /, $line;
	my $first = unpack 'a', $tmp[0];
	if (exists $hash{$first}) {
	    $hash{$first}{$num_viol} += $tmp[2];
	    next;
	}
	$hash{$first}{$num_viol} = int($tmp[2]);
    }
    return \%hash;
}

my @lines;
my $concatenated;
while (<>) { # Read all files that provided through ARGV
    chomp;
    if ($_ =~ /^\s*$/) {
	$. = 0;
	next;
    }
    elsif ($. == 1) {
	$concatenated .= $_;
    }
    elsif ($. == 3) {
	$concatenated .= $_;
	push @lines, $concatenated;
	$. = 0;
	$concatenated = '';
    }
} continue {
    close ARGV if eof; # reset $. each file
}

my $hash = extract_data(@lines);

my @final;
foreach my $violation (sort keys %$hash) {
    push @final, join(' ',
		      $violation,
		      $num_viol,
		      $$hash{$violation}{'number of violation(s)'});
}
print Dumper \@final;

__END__

$ perl test.pl in.txt
$VAR1 = [
          'A number of violation(s) 5',
          'B number of violation(s) 3'
        ];

__DATA__

A_01: xxxxxxx
xxxxxxxxxx
xxx......... 1 violation

A_02: xxxxxxx
xxxxxxxxxx
xxx......... 4 violations
B_02: xxxxxxx
xxxxxxxxxx
xxx......... 3 violations