Every day I realize I have more to learn. Your code is much more elegant than my recursive solution.

use warnings;
use strict;
use Data::Dumper;

my @lists = ([qw/Truck Car Bike/],
             [qw/Truck Car Scooter/],
             [qw/Truck Trailer Skates/]);

my %tree;

for my $list (@lists) {
    to_tree(\%tree, $list);
}

print Dumper(\%tree);

sub to_tree {
    my ($head, $list) = @_;
    my $node = shift @$list;

    return unless defined $node;

    $head->{$node} ||= {};
    to_tree($head->{$node}, $list);
}

[download]

In reply to Re^2: trees of word lists by lostjimmy
in thread trees of word lists by citromatik

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.