use strict; use warnings; sub prepare { my( $subtree, $level, $col, $graph ) = @_; my $lcol = 0; if( ref($subtree) ) { $lcol = prepare( $subtree->[0], $level+1, $col, $graph ); # parse left side of tree, keep top position $lcol and $graph->[$level]->[$_] = '_' for $lcol..$$col-1; # draw horizontal line $graph->[$level]->[$$col++] = '/'; $lcol = $$col; # new root of the tree $graph->[$level]->[$$col++] = '\\'; my $rcol = prepare( $subtree->[1], $level+1, $col, $graph ); # parse right side of the tree, keep its top position $rcol and $graph->[$level]->[$_] = '_' for $lcol+1..$rcol-1; # draw horizontal line } else { $graph->[$level]->[$$col++] = $subtree; # leaf } return $lcol; # return column of root } 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, 0, \$col, \@graph ); for my $row ( @graph ) { print $_ // ' ' for @$row; print "\n"; }