[LeetCode] Symmetric Tree

题目链接

bool isSymmetric(TreeNode *root) {
	vector<TreeNode*> left_nodes;
	vector<TreeNode*> right_nodes;
	if (root != NULL)
	{
		if(root->left != NULL)
		{
			left_nodes.push_back(root->left);
		}
		if(root->right != NULL)
		{
			right_nodes.push_back(root->right);
		}
	}
	while(!left_nodes.empty() && !right_nodes.empty())
	{
		TreeNode* left_node = left_nodes.back();
		TreeNode* right_node = right_nodes.back();

		if(left_node->val != right_node->val)
		{
			return false;
		}

		TreeNode* left_node_left = NULL;
		TreeNode* left_node_right = NULL;
		if(left_node->left != NULL)
		{
			left_node_left = left_node->left;
		}
		if(left_node->right != NULL)
		{
			left_node_right = left_node->right;
		}
		left_nodes.pop_back();

		TreeNode* right_node_left = NULL;
		TreeNode* right_node_right = NULL;
			if(right_node->left != NULL)
			{
				right_node_left = right_node->left;
			}
			if(right_node->right != NULL)
			{
				right_node_right = right_node->right;
			}
			right_nodes.pop_back();
			if(left_node_left != NULL && right_node_right != NULL)
			{
				left_nodes.push_back(left_node_left);
				right_nodes.push_back(right_node_right);   
			}
			else if(left_node_left == NULL && right_node_right == NULL)
			{                    
			}
			else
			{
				return false;
			}
			if(left_node_right != NULL && right_node_left != NULL)
			{
				left_nodes.push_back(left_node_right);
				right_nodes.push_back(right_node_left);   
			}
			else if(left_node_right == NULL && right_node_left == NULL)
			{
			}
			else
			{
				return false;
			}                          
	}
	if(left_nodes.size() == right_nodes.size())
	{
		return true;
	}
	else
	{
		return false;
	}
}