อยากทราบการทำงานของโค๊ด dijkstra อยากวอนให้ผู้ที่รู้ช่วยอธิบายโค๊ดในส่วนที่มีให้หน่อยค่ะ ขอบพระคุณล่วงหน้าค่ะ

<?PHP

class Dijkstra {

var $visited = array();
var $distance = array();
var $previousNode = array();
var $startnode =null;
var $map = array();
var $infiniteDistance = 0;
var $numberOfNodes = 0;
var $bestPath = 0;
var $matrixWidth = 0;

function Dijkstra(&$ourMap, $infiniteDistance) 
{
	$this -> infiniteDistance = $infiniteDistance;
	$this -> map = &$ourMap;
	$this -> numberOfNodes = count($ourMap);
	$this -> bestPath = 0;
}

function findShortestPath($start,$to = null)
{
	$this -> startnode = $start;
	for ($i=0;$i<$this -> numberOfNodes;$i++) 
	{
		if ($i == $this -> startnode) 
		{
			$this -> visited[$i] = true;
			$this -> distance[$i] = 0;
		} else {
				$this -> visited[$i] = false;
				$this -> distance[$i] = isset($this -> map[$this -> startnode][$i])
				? $this -> map[$this -> startnode][$i]
				: $this -> infiniteDistance;
				}
		$this -> previousNode[$i] = $this -> startnode;
	}

	$maxTries = $this -> numberOfNodes;
	$tries = 0;
	while (in_array(false,$this -> visited,true) && $tries <= $maxTries) 
	{
		$this -> bestPath = $this->findBestPath($this->distance,array_keys($this -> visited,false,true));
		if($to !== null && $this -> bestPath === $to) 
		{
			break;
		}
		$this -> updateDistanceAndPrevious($this -> bestPath);
		$this -> visited[$this -> bestPath] = true;
		$tries++;
	}
}

function findBestPath($ourDistance, $ourNodesLeft) 
{
	$bestPath = $this -> infiniteDistance;
	$bestNode = 0;
	for ($i = 0,$m=count($ourNodesLeft); $i < $m; $i++) 
	{
		if($ourDistance[$ourNodesLeft[$i]] < $bestPath) 
		{
			$bestPath = $ourDistance[$ourNodesLeft[$i]];
			$bestNode = $ourNodesLeft[$i];
		}
	}
	return $bestNode;
}

function updateDistanceAndPrevious($obp) 
{
	for ($i=0;$i<$this -> numberOfNodes;$i++) 
	{
		if( (isset($this->map[$obp][$i])) && (!($this->map[$obp][$i] == $this->infiniteDistance) || ($this->map[$obp][$i] == 0 )) && (($this->distance[$obp] + $this->map[$obp][$i]) < $this -> distance[$i]))
		{
			$this -> distance[$i] = $this -> distance[$obp] + $this -> map[$obp][$i];
			$this -> previousNode[$i] = $obp;
		}
	}
}

function printMap(&$map) 
{
	$placeholder = ' %' . strlen($this -> infiniteDistance) .'d';
	$foo = '';
	for($i=0,$im=count($map);$i<$im;$i++) 
	{
		for ($k=0,$m=$im;$k<$m;$k++) 
		{
			$foo.= sprintf($placeholder, isset($map[$i][$k]) ? $map[$i][$k] : $this -> infiniteDistance);
		}
	$foo.= "\n";
	}
	return $foo;
}

function getResults($to = null) 
{
	$ourShortestPath = array();
	$foo = '';
    for ($i = 0; $i < $this -> numberOfNodes; $i++) 

	{
		if($to !== null && $to !== $i) 
		{
			continue;
		}
		$ourShortestPath[$i] = array();
		$endNode = null;
		$currNode = $i;
		$ourShortestPath[$i][] = $i;
		while ($endNode === null || $endNode != $this -> startnode) 
		{
			$ourShortestPath[$i][] = $this -> previousNode[$currNode];
			$endNode = $this -> previousNode[$currNode];
			$currNode = $this -> previousNode[$currNode];
		}
		$ourShortestPath[$i] = array_reverse($ourShortestPath[$i]);
		if ($to === null || $to === $i) 
		{
			if($this -> distance[$i] >= $this -> infiniteDistance) 
			{
				$foo .= sprintf("ไม่่มีเส้น path จากจากโหนด %d ในรอบ•ี่ %d. \n",$this -> startnode,$i);
			} else {
					
					$foo .= sprintf($this -> distance[$i]);
				
					}
		
			if ($to === $i) 
			{
				break;
			}
		}
		
	}
	return $foo;
}
} 
?>