LeetCode 之 Invert Binary Tree

LeetCode : Invert Binary Tree 
題目原意：反轉一棵二叉樹，即交換樹的每一個左右節點； 

代碼如下（leetCode 測得運行時間爲0ms）：

struct TreeNode *invertTree(struct TreeNode *root)
{
	struct TreeNode *tmp = NULL;

	if (root == NULL)
	{
		return NULL;
	}

	//!< 先交換左右節點，再分別對左右節點遞歸
	tmp = root->right;
	root->right = root->left;
	root->left  = tmp;

	if (root->right)
	{
		invertTree(root->right);
	}

	if (root->left)
	{
		invertTree(root->left);
	}

	return root;
}