...
my %best;
while (my $line=<YOURFILE>) {
  chomp $line;
  my ($item,$group,count)= split(/\s+/,$line);
  if ((not exists $best{$group}) or $best{$group}{count}<$count) {
    $best{$group}{count}=$count;
    $best{$group}{item}= $item;
  }
}


#to print them out
foreach my $group ( keys %best) {
  print "$best{$group}{item} $group $best{$group}{count}\n";
}