把二叉樹打印成多行

題目描述：從上到下按層打印二叉樹，同一層的結點按從左到右的順序打印，每一層打印到一行，例如：

void Print()
{
	if (_root == NULL)
		return;
	queue<Node*>q;
	q.push(_root);
	int NextLevel = 0; //下一行結點的個數
	int CurLevel = 1;  //當前行結點的個數
	while (!q.empty())
	{
		Node* front = q.front();
		cout << front->_value << " ";
		q.pop();
		CurLevel--;
		if (front->_left)
		{
			q.push(front->_left);
			NextLevel++;
		}
		if (front->_right)
		{
			q.push(front->_right);
			NextLevel++;
		}
		if (CurLevel == 0) //說明該行的結點都已被打印
		{
			printf("\n");
			CurLevel = NextLevel;
			NextLevel = 0;
		}
	}
}