my $str = 'aabcdabcabcecdecd';

##</code><code>##

(abc => 3, bc => 3, cd => 3, ecd => 2)

##</code><code>##

sub count1 {
    local $_=shift;
    my %count;
    
    for my $pos (0..(length)-1) {
        pos=$pos;
        @count{ /(.{2,}).*\1/g } = ();
    }
    
    for my $k (keys %count) {
        $count{$k} =()= /$k/g;
    }

    \%count;
}

##</code><code>##

$VAR1 = {
          'cd' => 3,
          'ecd' => 2,
          'abc' => 3,
          'bc' => 3
        };

##</code><code>##

$VAR1 = {
          'cd' => 3,
          'c' => 5,
          'ecd' => 2,
          'a' => 4,
          'abc' => 3,
          'd' => 3,
          'bc' => 3
        };

##</code><code>##

sub count2 {
    my $s=shift;
    my %saw;
    my %count = map {
        map {
            $saw{$_}++ ? () : 
              $_ => scalar(()= $s =~ /$_/g);
        } do { pos=$_; $s =~ /(.{2,}).*\1/g };
    } 0..length($s)-1;
    \%count;
}

##</code><code>##

$VAR1 = {
          'ecd' => 2,
          'abc' => 3,
          '3' => 2
        };