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use strict;
use warnings;
...
$matrix[$first][$last] = $count if (++$first == $last);
buildRing ($first, $last) if ($first<$last);
}

use strict;
use warnings;
...

my $width = (int log $count) - 1;
print "" . (join " ", map {sprintf "%${width}d", $_} @{$matrix[$_]}) .
+ "\n" for (0..($n-1));

$n=shift;($c,$f,$l,@m)=(1,0,--$n);
{$m[$f][$_]=$c++for($f..$l);$m[$_][$l]=$c++for($f+1..$l);
$m[$l][$l-$_+$f-1]=$c++for($f..$l-1);for($_=--$l;$_>$f;--$_){$m[$_][$f
+]=$c++}
$m[$f][$l]=$c if(++$f==$l);redo unless$f>$l}my$w=(int log$c);
print"".(join"",map{sprintf"%${w}d",$_}@{$m[$_]})."\n"for(0..$n)