# Check for continuous binary tree in php

``````<?php
/*
Php program for
Check if binary tree is continuous tree
Using recursion
*/
// Binary Tree Node
class TreeNode
{
public \$data;
public \$left;
public \$right;
public	function __construct(\$data)
{
// Set node value
\$this->data = \$data;
\$this->left = NULL;
\$this->right = NULL;
}
}
class BinaryTree
{
public \$root;
public	function __construct()
{
\$this->root = NULL;
}
public	function absValue(\$num)
{
if (\$num < 0)
{
return -\$num;
}
return \$num;
}
// Check tree is continuous or not
public	function isContinuous(\$node)
{
if (\$node != NULL)
{
if ((\$node->left != NULL &&
\$this->absValue(\$node->data - \$node->left->data) != 1) ||
(\$node->right != NULL &&
\$this->absValue(\$node->data - \$node->right->data) != 1))
{
// Case
// When fail continuous tree rule
return false;
}
if (\$this->isContinuous(\$node->left) &&
\$this->isContinuous(\$node->right))
{
return true;
}
// When node value is not satisfied
//  continuous tree properties
return false;
}
return true;
}
public static
function main(\$args)
{
// Create new tree
\$tree = new BinaryTree();
/*
Binary Tree
------------
5
/   \
4     4
/     /  \
3     5    3
\
2

*/
\$tree->root = new TreeNode(5);
\$tree->root->left = new TreeNode(4);
\$tree->root->right = new TreeNode(4);
\$tree->root->left->left = new TreeNode(3);
\$tree->root->right->right = new TreeNode(3);
\$tree->root->right->left = new TreeNode(5);
\$tree->root->left->left->right = new TreeNode(2);
if (\$tree->isContinuous(\$tree->root) == true)
{
echo "Continuous Tree \n";
}
else
{
echo "Not Continuous Tree \n";
}
// Case 2
/*
5
/   \
4     4
/     /  \
3     5    3
\
1  <--- change value

*/
\$tree->root->left->left->right->data = 1;
if (\$tree->isContinuous(\$tree->root) == true)
{
echo "Continuous Tree \n";
}
else
{
echo "Not Continuous Tree \n";
}
}
}
BinaryTree::main(array());``````

Output

``````Continuous Tree
Not Continuous Tree``````

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