ikegami,
Your code:

my %count;
++$count{$_} foreach @c;

my @pairs = grep { $count{$_} >= 2 } sort { $b <=> $a } @c;
my @kind3 = grep { $count{$_} >= 3 } @pairs;
my @kind4 = grep { $count{$_} >= 4 } @kind3;
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Can be simplified to:

my ($points, %count);
++$count{$_} for @c;
$points += $_ * ($_ - 1) for values %count;
[download]

I used this trick and several others in RFC: Cribbage::Hand.