use strict;

my $debug = 0;

my @data  = <DATA>;
my $count = @data;
print "Original: $count\n";

# first run which cannot be worse than the whole file
my @result = try_me(@data);
my $result = @result;
print "Run 1:  $result\n";
print @result;

#we will unloop $unloop_factor records each time and see if we get a better result
my $unloop_factor = 3;

#we will try this $number_of_runs times
my $number_of_runs = 5000;

foreach my $number ( 2 .. $number_of_runs + 1 ) {
    my @new_data = unloop( $unloop_factor, @data );
    print "New data:\n @new_data" if $debug;
    my @new_result = try_me(@new_data);
    my $new_result = @new_result;
    print "Run $number: $new_result\n" if $debug;
    if ( $new_result <= $result ) {
        print "New result:\n @new_result" if $debug;
        @data   = @new_data;
        @result = @new_result;
        $result = $new_result;
    } ## end if ( $new_result <= $result)
} ## end foreach my $number ( 2 .. $number_of_runs...
print "\nFinal result is: $result\n @result\n";

sub unloop {
    my ( $unloop_factor, @data ) = @_;
    my $length = @data;
    my $start  = int( rand( $length - $unloop_factor ) );
    print "\nUnloop after $start\n" if $debug;
    my @begin  = @data[ 0 .. $start ];
    my @middle = @data[ $start + 1 .. $start + $unloop_factor ];
    my @end = ( @data, @data )[ $start + $unloop_factor + 1 .. $length - 1 ];
    return ( @begin, reverse(@middle), @end );
} ## end sub unloop

sub try_me {
    my @input = @_;
    my @result;
    my ( %first, %second, %third );
    foreach (@input) {
        my ( $first, $second, $third, $fourth ) = split ',';
        push @result, $_
            unless exists $first{$first}
                and exists $second{$second}
                and exists $third{$third};
        $first{$first}++;
        $second{$second}++;
        $third{$third}++;
    } ## end foreach (@input)
    return @result;
} ## end sub try_me

__DATA__
A1, B1, C1, first record*
A2, B1, C3, second record
A3, B1, C2, third record
A1, B2, C3, fourth record
A2, B2, C2, fifth record*
A3, B2, C1, sixth record
A1, B3, C2, seventh record
A2, B3, C1, eight record
A3, B3, C3, nineth record*
A1, B2, C3, tenth record