在PHP中,可以使用序列化将二叉树转换为字符串表示形式,以便存储或传输。以下是一个简单的PHP类,用于表示二叉树节点以及实现序列化和反序列化的方法:
class TreeNode {
public $val;
public $left;
public $right;
public function __construct($val = 0, $left = null, $right = null) {
$this->val = $val;
$this->left = $left;
$this->right = $right;
}
}
class Codec {
// Encodes a tree to a single string.
public function serialize($root) {
if ($root === null) {
return 'null,';
}
return $root->val . ',' . $this->serialize($root->left) . ',' . $this->serialize($root->right);
}
// Decodes your encoded data to tree.
public function deserialize($data) {
$dataArray = explode(',', trim($data, '[]'));
return $this->buildTree($dataArray);
}
private function buildTree($dataArray) {
if (empty($dataArray)) {
return null;
}
$val = array_shift($dataArray);
if ($val === 'null') {
return null;
}
$node = new TreeNode($val);
$node->left = $this->buildTree($dataArray);
$node->right = $this->buildTree($dataArray);
return $node;
}
}
使用此类,您可以创建一个二叉树节点实例,序列化它,然后将其反序列化回原始结构。以下是如何使用此类的示例:
$root = new TreeNode(1);
$root->left = new TreeNode(2);
$root->right = new TreeNode(3);
$root->right->left = new TreeNode(4);
$root->right->right = new TreeNode(5);
$codec = new Codec();
$serialized = $codec->serialize($root);
echo "Serialized tree: " . $serialized . PHP_EOL; // 输出:Serialized tree: 1,2,null,null,3,4,null,null,5,
$deserialized = $codec->deserialize($serialized);
var_dump($deserialized); // 输出:object(TreeNode)#3 (3) { ["val"]=> int(1) ["left"]=> object(TreeNode)#4 (3) { ["val"]=> int(2) ["left"]=> object(TreeNode)#5 (3) { ["val"]=> int(4) ["left"]=> NULL ["right"]=> NULL } ["right"]=> NULL } ["right"]=> object(TreeNode)#6 (3) { ["val"]=> int(3) ["left"]=> NULL ["right"]=> NULL } ["right"]=> object(TreeNode)#7 (3) { ["val"]=> int(5) ["left"]=> NULL ["right"]=> NULL } } ["left"]=> NULL ["right"]=> NULL }