http://www.perlmonks.org?node_id=400400


in reply to Recursion: The Towers of Hanoi problem

As always there are non recursive solutions. This one is 14 lines long if you exclude the animation code.

#!/usr/bin/perl -w print "Number of disks? "; chomp( my $numdisks = <STDIN> ); print "Sleep? "; chomp( my $sleep = <STDIN> ); $numdisks ||= 8; $sleep ||= 0.1; my $board = [ [], [], [], [] ]; push @{$board->[1]}, $_ for reverse 1 .. $numdisks; my %tower = map{ my $str =' 'x($numdisks-$_).'o'x$_; $str = $str.($_?'+':'|').reverse($str); $_, " $str " } 0..$numdisks; hanoi( $numdisks ); sub hanoi { my $n = shift; my $n1 = $n+1; my @D = (1)x$n1; my @s = 1..$n1+1; my $dir = 1 & $n; for(;;) { my $i = $s[0]; do{ show($n,0,0,1); last } if $i>$n; my $to =($D[$i]+($i&1?$dir:1-$dir))%3+1; show( $i, $D[$i], $to ); $D[$i] = $to; $s[0] = 1; $s[$i-1] = $s[$i]; $s[$i] = $i+1; } } sub show { my ( $num, $from, $to, $show_final ) = @_; $^O =~ m/Win32/ ? system("cls") : system("clear"); for my $i( reverse 0..$numdisks ) { print "\n", map{$tower{ $board->[$_]->[$i] || 0} }1..3; } return if $show_final; push @{$board->[$to]}, pop @{$board->[$from]}; print "\n\nMove disk $num from $from to $to\n"; select undef, undef, undef, $sleep; }

cheers

tachyon