Jun 24, 2024 · May 26, 2024 · May 30, 2024 · May 31, 2024 · Jun 24, 2024 · Jun 24, 2024
diff --git a/problems/二叉树的递归遍历.md b/problems/二叉树的递归遍历.md
Original file line number	Diff line number	Diff line change
Expand Up		@@ -671,6 +671,62 @@ public void Traversal(TreeNode cur, IList<int> res)
		}
		```

	### PHP
	```php
	// 144.前序遍历
	function preorderTraversal($root) {
	$output = [];
	$this->traversal($root, $output);
	return $output;
	}

	function traversal($root, array &$output) {
	if ($root->val === null) {
	return;
	}

	$output[] = $root->val;
	$this->traversal($root->left, $output);
	$this->traversal($root->right, $output);
	}
	```
	```php
	// 94.中序遍历
	function inorderTraversal($root) {
	$output = [];
	$this->traversal($root, $output);
	return $output;
	}

	function traversal($root, array &$output) {
	if ($root->val === null) {
	return;
	}

	$this->traversal($root->left, $output);
	$output[] = $root->val;
	$this->traversal($root->right, $output);
	}
	```
	```php
	// 145.后序遍历
	function postorderTraversal($root) {
	$output = [];
	$this->traversal($root, $output);
	return $output;
	}

	function traversal($root, array &$output) {
	if ($root->val === null) {
	return;
	}

	$this->traversal($root->left, $output);
	$this->traversal($root->right, $output);
	$output[] = $root->val;
	}
	```


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