Sometimes I find with recursion it helps to add some tracking to help visualise what path is being followed.

Hope this helps

use warnings;
use strict;

my $ndisks = 3;
hanoi( $ndisks, 'A', 'C', 'B', 0 );

sub hanoi 
{
        my( $n, $start, $end, $extra, $depth ) = @_;

        print "\t"x$depth . "n=$n, start=$start end=$end extra=$extra\
+n";

        if( $n == 1 )
        {
                print "\t"x$depth . "Move disk #$n from $start to $end
+\n";
        }
        else
        {
                $depth++;
                print "\t"x$depth . "Calling hanoi 1\n";
                hanoi( $n-1, $start, $extra, $end, $depth);
                print "\t"x$depth . "Move disk #$n from $start to $end
+\n";
                print "\t"x$depth . "Calling hanoi 2\n";
                hanoi ($n-1, $extra, $end, $start, $depth);
        }
}
[download]

n=3, start=A end=C extra=B
    Calling hanoi 1
    n=2, start=A end=B extra=C
        Calling hanoi 1
        n=1, start=A end=C extra=B
        Move disk #1 from A to C
        Move disk #2 from A to B
        Calling hanoi 2
        n=1, start=C end=B extra=A
        Move disk #1 from C to B
    Move disk #3 from A to C
    Calling hanoi 2
    n=2, start=B end=C extra=A
        Calling hanoi 1
        n=1, start=B end=A extra=C
        Move disk #1 from B to A
        Move disk #2 from B to C
        Calling hanoi 2
        n=1, start=A end=C extra=B
        Move disk #1 from A to C
[download]