从上到下遍历二叉树--20150925

//从上倒下出从左到右打印二叉树//思路：利用队列先进先出的特性，先将根节点从队尾入队列，//再从队头出队列并打印，再将其左子树从队尾入队列并打印，//再将右子树入队列并打印，递归下去。//二叉树节点结构struct BTreeNode{    int value;    BTreeNode* pLeft;    BTreeNode* pRight;}void PrintFromTopToButton(BTreeNode* pTreeRoot){    if(!pTreeRoot){        return;    }    std::deque<BTreeNode*>dequeTreeNode;    dequeTreeNode.push_back(pTreeRoot);    while(dequeTreeNode.size()){        BTreeNode* pNode = dequeTreeNode.front();        dequeTreeNode.pop_front();        printf("%d",pNode->value);        if(pNode->pLeft){            dequeTreeNode.push_back(pNode->pLeft);        }        if(pNode->pRight){            dequeTreeNode.push_back(pNode->pRight);        }    }}