Insertion in binary search tree using recursion in php
Php program for Insertion in binary search tree using recursion. Here problem description and explanation.
<?php
// Php program for
// Insertion in binary search tree by using recursion
class TreeNode
{
public $data;
public $left;
public $right;
public function __construct($data)
{
$this->data = $data;
$this->left = NULL;
$this->right = NULL;
}
}
class BinarySearchTree
{
public $root;
public function __construct()
{
$this->root = NULL;
}
// Insert a node element
public function addNode($node, $data)
{
if ($node != NULL)
{
if ($node->data >= $data)
{
// When new element is smaller or
// equal to current node
$node->left =
$this->addNode($node->left, $data);
}
else
{
// When new element is higher to current node
$node->right =
$this->addNode($node->right, $data);
}
// important to manage root node
return $node;
}
else
{
return new TreeNode($data);
}
}
// Display preorder
public function preorder($node)
{
if ($node != NULL)
{
// Display node value
echo " ".strval($node->data);
// Visit to left subtree
$this->preorder($node->left);
// Visit to right subtree
$this->preorder($node->right);
}
}
public function inorder($node)
{
if ($node != NULL)
{
// Visit to left subtree
$this->inorder($node->left);
// Display node value
echo " ".strval($node->data);
// Visit to right subtree
$this->inorder($node->right);
}
}
public function postorder($node)
{
if ($node != NULL)
{
// Visit to left subtree
$this->postorder($node->left);
// Visit to right subtree
$this->postorder($node->right);
// Display node value
echo " ".strval($node->data);
}
}
public static function main()
{
$tree = new BinarySearchTree();
/*
10
/ \
/ \
4 15
/ \ /
3 5 12
-------------
Build binary search tree
*/
$tree->root = $tree->addNode($tree->root, 10);
$tree->addNode($tree->root, 4);
$tree->addNode($tree->root, 3);
$tree->addNode($tree->root, 5);
$tree->addNode($tree->root, 15);
$tree->addNode($tree->root, 12);
// Display tree nodes
echo "Preorder\n";
$tree->preorder($tree->root);
echo "\nInorder\n";
$tree->inorder($tree->root);
echo "\nPostorder\n";
$tree->postorder($tree->root);
}
}
BinarySearchTree::main();
Output
Preorder
10 4 3 5 15 12
Inorder
3 4 5 10 12 15
Postorder
3 5 4 12 15 10
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