Find indegree and outdegree of a directed graph in php

Php program for Find indegree and outdegree of a directed graph. Here more information.

<?php
/*
    Php Program for 
    Show degree of vertex in directed graph
*/
class AjlistNode
{
	// Vertices node key
	public $id;
	public $next;
	public	function __construct($id)
	{
		// Set value of node key
		$this->id = $id;
		$this->next = NULL;
	}
}

class Vertices
{
	public $data;
	public $next;
	public $last;
	public	function __construct($data)
	{
		$this->data = $data;
		$this->next = NULL;
		$this->last = NULL;
	}
}

class Graph
{
	// Number of Vertices
	public $size;
	public $node;
	public	function __construct($size)
	{
		// Set value
		$this->size = $size;
		$this->node = array_fill(0, $size, NULL);
		$this->setData();
	}
	// Set initial node value
	public	function setData()
	{
		if ($this->size <= 0)
		{
			printf("\nEmpty Graph\n");
		}
		else
		{
			for ($index = 0; $index < $this->size; $index++)
			{
				// Set initial node value
				$this->node[$index] = new Vertices($index);
			}
		}
	}
	//  Handling the request of adding new edge
	public	function addEdge($start, $last)
	{
		if ($start >= 0 && $start < $this->size && 
            $last >= 0 && $last < $this->size)
		{
			// Safe connection
			$edge = new AjlistNode($last);
			if ($this->node[$start]->next == NULL)
			{
				$this->node[$start]->next = $edge;
			}
			else
			{
				// Add edge at the end
				$this->node[$start]->last->next = $edge;
			}
			// Get last edge 
			$this->node[$start]->last = $edge;
		}
		else
		{
			// When invalid nodes
			printf("\nHere Something Wrong\n");
		}
	}
	public	function printGraph()
	{
		if ($this->size > 0)
		{
			// Print graph ajlist Node value
			for ($index = 0; $index < $this->size; ++$index)
			{
				printf("\nAdjacency list of vertex %d : ",$index);
				$temp = $this->node[$index]->next;
				while ($temp != NULL)
				{
					// Display graph node 
					printf("%d ",$this->node[$temp->id]->data);
					// Visit to next edge
					$temp = $temp->next;
				}
			}
		}
	}
	// Find indegree and outdegree of 
	// each nodes of a given graph
	public	function findDegree(&$indegree, &$outdegree)
	{
		$temp = NULL;
		$length = 0;
		for ($i = 0; $i < $this->size; ++$i)
		{
			$temp = $this->node[$i]->next;
			$length = 0;
			while ($temp != NULL)
			{
				// Update indegree
				$indegree[$temp->id]++;
				$temp = $temp->next;
				$length++;
			}
			// Set outdegree value
			$outdegree[$i] = $length;
		}
	}
	public	function showDegree()
	{
		if ($this->node != NULL)
		{
			$indegree = array_fill(0, $this->size, 0);
			$outdegree = array_fill(0, $this->size, 0);
			// Set zero degree
			for ($i = 0; $i < $this->size; $i++)
			{
				$indegree[$i] = 0;
				$outdegree[$i] = 0;
			}
			// Find degree
			$this->findDegree($indegree, $outdegree);
			printf("\n\n");
			// Display result
			for ($i = 0; $i < $this->size; ++$i)
			{
				printf("%s\n", "Node [".strval($i).
					"] indegree [".strval($indegree[$i]).
					"] outdegree [".strval($outdegree[$i]).
					"]");
			}
		}
		else
		{
			printf("Empty Graph");
		}
	}
	public static
	function main($args)
	{
		// 6 implies the number of nodes in graph
		$g = new Graph(6);
		// Connected two node with Edges
		$g->addEdge(0, 1);
		$g->addEdge(0, 2);
		$g->addEdge(0, 5);
		$g->addEdge(2, 3);
		$g->addEdge(3, 1);
		$g->addEdge(4, 0);
		$g->addEdge(4, 1);
		$g->addEdge(5, 0);
		$g->addEdge(5, 2);
		$g->printGraph();
		// Test
		$g->showDegree();
	}
}
Graph::main(array());

Output

Adjacency list of vertex 0 : 1 2 5
Adjacency list of vertex 1 :
Adjacency list of vertex 2 : 3
Adjacency list of vertex 3 : 1
Adjacency list of vertex 4 : 0 1
Adjacency list of vertex 5 : 0 2

Node [0] indegree [2] outdegree [3]
Node [1] indegree [3] outdegree [0]
Node [2] indegree [2] outdegree [1]
Node [3] indegree [1] outdegree [1]
Node [4] indegree [0] outdegree [2]
Node [5] indegree [1] outdegree [2]