/**
* Check whether another node is near by the their identifier
*
* @param Node $otherNode
* @return bool
*/
public function isNear(Node $otherNode)
{
$otherIdentifier = $otherNode->getIdentifier();
if ($otherIdentifier->getSize() != $this->identifier->getSize()) {
return false;
}
$differences = 0;
for ($i = 0; $i < $this->dimensions; $i++) {
if ($otherIdentifier[$i] != $this->identifier[$i]) {
$differences++;
}
if ($differences > 1) {
return false;
}
}
return true;
}
/**
* Recursive search step
*
* @param Node $currentNode
* @param array $unavailable
* @param array $path
* @param WeightedNodeCollection $wNodes
* @return array
*/
public function step(Node $currentNode, array $unavailable, array $path, WeightedNodeCollection $wNodes = null)
{
$currentString = $currentNode->getStringIdentifier();
$neighbors = $currentNode->computeNeighbors();
$exploredPaths = array();
$randomChoice = mt_rand(0, $this->dimensions - 1);
$randomCount = 0;
$randomAttempts = 0;
$unavailable[] = $currentString;
// Use weight information when available
if (!is_null($wNodes) && $wNodes->hasStatisticsFor($currentString)) {
$randomChoice = array_search($wNodes->getNode($currentString)->getBiasedNeighborChoice(), $neighbors);
}
foreach ($neighbors as $neighborString) {
// Randomization
if ($this->isRandomized()) {
if ($randomChoice != $randomCount) {
$randomCount++;
continue;
}
$randomCount++;
if (in_array($neighborString, $unavailable)) {
$randomChoice = mt_rand(0, $this->dimensions - 1);
$randomAttempts++;
$randomCount = 0;
// Give up if it is a dead end
if ($randomAttempts > $this->dimensions) {
break;
}
continue;
}
} elseif (in_array($neighborString, $unavailable)) {
continue;
}
// Recursively navigate into the node
$neighbor = new Node($this->dimensions, $neighborString);
// Clone paths
$neighborPath = array_merge($path);
// Add path taken
$neighborPath[] = array($currentString, $neighborString);
// Add this node and other neighbors
$neighborUnavailable[] = $neighbor->getStringIdentifier();
$otherNeighbors = array_diff($neighbors, array($neighborString));
$neighborUnavailable = array_merge($unavailable, array($currentString), $otherNeighbors);
$newPath = $this->step($neighbor, $neighborUnavailable, $neighborPath);
$exploredPaths[] = $newPath;
}
/*echo "\nExplored: " . count($exploredPaths) . "\n";
echo "Current: " . $currentString . "\n";
echo "Neighbors: \n";
print_r($neighbors);
echo "Unavailable: \n";
print_r($unavailable);*/
// Find largest path explored
$largestPathLength = 0;
$largestPath = $path;
foreach ($exploredPaths as $exploredPath) {
$length = count($exploredPath);
if ($length > $largestPathLength) {
$largestPath = $exploredPath;
$largestPathLength = $length;
}
}
return $largestPath;
}
