二叉树镜像

镜像——照镜子得出的像。特征就是左右反着，如下图

思路

仿着递归遍历，递归得到镜像

• 输入结点指针p不为空且部位叶子，反转p的左右孩子
• 找p的左孩子的镜像
• 找p的右孩子的镜像

参考代码

void getImage(BinaryTreeNode *root)

{

    if(root != NULL && root->m_pLeft != NULL && root->m_pRight != NULL)

    {

        BinaryTreeNode *temp = root->m_pLeft;

        root->m_pLeft = root->m_pRight;

        root->m_pRight = temp;

        getImage(root->m_pLeft);

        getImage(root->m_pRight);

    }

}

注意

有需要判断一下叶子结点（当然可以不判断是否为叶子，但是判断叶子两句，反转三句话）

完整运行

#include <iostream>

using namespace std;

struct BinaryTreeNode

{

    int m_nValue;

    BinaryTreeNode *m_pLeft;

    BinaryTreeNode *m_pRight;

};

void CreateTree(BinaryTreeNode *root)

{

    BinaryTreeNode *p1 = new(BinaryTreeNode);

    p1->m_nValue = 8;

    p1->m_pLeft = NULL;

    p1->m_pRight = NULL;

    root->m_pLeft = p1;



    BinaryTreeNode *p2 = new(BinaryTreeNode);

    p2->m_nValue = 7;

    p2->m_pLeft = NULL;

    p2->m_pRight = NULL;

    root->m_pRight = p2;



    BinaryTreeNode *p3 = new(BinaryTreeNode);

    p3->m_nValue = 9;

    p3->m_pLeft = NULL;

    p3->m_pRight = NULL;

    p1->m_pLeft = p3;



    BinaryTreeNode *p4 = new(BinaryTreeNode);

    p4->m_nValue = 2;

    p4->m_pLeft = NULL;

    p4->m_pRight = NULL;

    p1->m_pRight = p4;



    BinaryTreeNode *p5 = new(BinaryTreeNode);

    p5->m_nValue = 4;

    p5->m_pLeft = NULL;

    p5->m_pRight = NULL;

    p4->m_pLeft = p5;



    BinaryTreeNode *p6 = new(BinaryTreeNode);

    p6->m_nValue = 7;

    p6->m_pLeft = NULL;

    p6->m_pRight = NULL;

    p4->m_pRight = p6;

}

void MidTraverse(BinaryTreeNode *root)

{

    if(root != NULL)

    {

        MidTraverse(root->m_pLeft);

        cout << root->m_nValue << " ";

        MidTraverse(root->m_pRight);

    }

}



void DeleteTree(BinaryTreeNode *root)

{

    if(root != NULL)

    {

        DeleteTree(root->m_pLeft);

        DeleteTree(root->m_pRight);

        delete(root);

        root = NULL;

    }

}



void getImage(BinaryTreeNode *root)

{

    if(root != NULL && root->m_pLeft != NULL && root->m_pRight != NULL)

    {

        BinaryTreeNode *temp = root->m_pLeft;

        root->m_pLeft = root->m_pRight;

        root->m_pRight = temp;

        getImage(root->m_pLeft);

        getImage(root->m_pRight);

    }

}

int main()

{

    BinaryTreeNode *root = new(BinaryTreeNode);

    root->m_nValue = 8;

    root->m_pLeft = NULL;

    root->m_pRight = NULL;



    CreateTree(root);

    MidTraverse(root);

    cout << endl;



    getImage(root);



    MidTraverse(root);

    cout << endl;

    DeleteTree(root);

}

View Code

结果

9 8 4 2 7 8 7
7 8 7 2 4 8 9