剑指offer——面试题32：从上到下打印二叉树

void BFS(BinaryTreeNode* pRoot)

{

    if(pRoot==nullptr)

    {

        cout<<"empty binary tree!"<<endl;

        return;

    }

    queue<BinaryTreeNode*>pNode;

    pNode.push(pRoot);

    while(!pNode.empty())

    {

        BinaryTreeNode* pFront=pNode.front();

        pNode.pop();

        cout<<pFront->m_Value<<' ';

        if(pFront->m_pLeft!=nullptr)

            pNode.push(pFront->m_pLeft);

        if(pFront->m_pRight!=nullptr)

            pNode.push(pFront->m_pRight);

    }

    cout<<endl;

}

函数

 #include"BinaryTree.h"

 void Test()

 {

     BFS(nullptr);

     BinaryTreeNode* pNode1=CreateBinaryTreeNode();

     BFS(pNode1);

     BinaryTreeNode* pNode2=CreateBinaryTreeNode();

     ConnectTreeNodes(pNode1,pNode2,nullptr);

     BFS(pNode1);

     ConnectTreeNodes(pNode1,nullptr,pNode2);

     BFS(pNode1);

     BinaryTreeNode* pNode3=CreateBinaryTreeNode();

     ConnectTreeNodes(pNode1,pNode2,pNode3);

     BFS(pNode1);

 }

 int main()

 {

     Test();

     return ;

 }

测试代码