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