BST Insert - Perl DSA

Insert values into a binary search tree by comparing at each node.

Algorithm

The canonical tree is 4(2(1,3),6(5,7)), so this Perl DSA implementation can be compared directly with the rest of the DSA track.

Basic Implementation

basic.pl

use strict;
use warnings;
sub node { my ($value, $left, $right) = @_; return { value => $value, left => $left, right => $right }; }
sub render {
    my ($node) = @_;
    return "_" unless defined $node;
    return "$node->{value}" unless defined $node->{left} || defined $node->{right};
    return "$node->{value}(" . render($node->{left}) . "," . render($node->{right}) . ")";
}
sub sample_tree {
    return node(4, node(2, node(1), node(3)), node(6, node(5), node(7)));
}
sub list_string { return "[" . join(", ", @_) . "]"; }
sub insert { my ($root, $value) = @_; return node($value) unless defined $root; if ($value < $root->{value}) { $root->{left} = insert($root->{left}, $value); } else { $root->{right} = insert($root->{right}, $value); } return $root; }
my $root; for my $value (4, 2, 6, 1, 3, 5, 7) { $root = insert($root, $value); } print render($root) . "\n";

Complexity

Time: O(h) per insert
Space: O(n)

Implementation notes

Render tree structure explicitly instead of printing node objects.
The replay highlights the node, traversal state, queue, path, or search cursor that changes at each step.

binary search tree Values smaller than a node go left; larger values go right.