use strict; use warnings; use constant { LEFT => 0, RIGHT => 1 }; sub prepare { my( $subtree, $lr, $level, $col, $graph ) = @_; if( ref($subtree) ) { my $lcol = prepare( $subtree->[LEFT ], LEFT, $level+1, $col, $graph ); $$col+=2; my $rcol = prepare( $subtree->[RIGHT], RIGHT, $level+1, $col, $graph ); $graph->[$level]->[$lcol] = '/'; $graph->[$level-1]->[$_] = '_' for $lcol+1..$rcol-1; $graph->[$level]->[$rcol] = '\\'; return $lr == LEFT ? $rcol : $lcol; # intentionally the other way round !! } else { $graph->[$level]->[$$col] = $subtree; return $$col; } } my $root = do { my $r; my @a = ( 'a'..'z', 1..9, 'A'..'Z' ); $r = int( rand $#a ), splice @a, $r, 2, [ @a[ $r, $r+1 ]] while @a > 1; $a[0]; }; my @graph; my $col = 0; prepare( $root, LEFT, 1, \$col, \@graph ); # need to start with $level = 1 ! for my $row ( @graph ) { print $_ // ' ' for @$row; print "\n"; }