二叉树的层次遍历法

void print_by_level_2(treeNode* Root) { 
　　if(! Root)
　　   return;
    deque<treeNode*> dequeTreeRoot;  
    dequeTreeRoot.push_back(Root);  
    while(!dequeTreeRoot.empty()) {  
            treeNode *temp = dequeTreeRoot.front();  
            dequeTreeRoot.pop_front();  
            cout << temp->data << " ";  
            if (temp->lchild)  
                dequeTreeNode.push_back(temp->lchild);  
            if (temp->rchild)  
                dequeTreeNode.push_back(temp->rchild);  
    }//end while  
}