剑指offer——二叉树

最新推荐文章于 2025-09-09 20:07:09 发布

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CC 4.0 BY-SA版权

文章标签：数据结构与算法

原文链接：http://www.cnblogs.com/acm-jing/p/10425571.html

本文介绍了一种用于判断一棵二叉树是否为另一棵二叉树子树的算法。通过递归比较两棵树的节点值，实现对子树的精确匹配。文章详细展示了创建二叉树节点、连接节点、打印树结构以及销毁树等操作，并提供了完整的C++代码实现。

#include"iostream"
#include"stdio.h"
#include"math.h"
using namespace std;

struct BinaryTreeNode
{
    double m_Value;
    BinaryTreeNode* m_pLeft;
    BinaryTreeNode* m_pRight;
};

BinaryTreeNode* CreateBinaryTreeNode(double value)
{
    BinaryTreeNode* pNode=new BinaryTreeNode();
    pNode->m_Value=value;
    pNode->m_pLeft=nullptr;
    pNode->m_pRight=nullptr;

    return pNode;
}

void ConnectTreeNodes(BinaryTreeNode* pParent,BinaryTreeNode* pLeft,BinaryTreeNode* pRight)
{
    if(pParent!=nullptr)
    {
        pParent->m_pLeft=pLeft;
        pParent->m_pRight=pRight;
    }
}

void PrintTreeNode(const BinaryTreeNode* pNode)
{
    if(pNode!=nullptr)
    {
        cout<<"value of this node is:"<<pNode->m_Value<<endl;

        if(pNode->m_pLeft!=nullptr)
            cout<<"value of its left child is:"<<pNode->m_pLeft->m_Value<<endl;
        else
            cout<<"left child is nullptr."<<endl;
        if(pNode->m_pRight!=nullptr)
            cout<<"value of its right child is:"<<pNode->m_pRight->m_Value<<endl;
        else
            cout<<"right child is nullptr."<<endl;
    }
    else
        cout<<"this node is nullptr."<<endl;
    cout<<endl;
}

void PrintTree(const BinaryTreeNode* pRoot)
{
    PrintTreeNode(pRoot);

    if(pRoot!=nullptr)
    {
        if(pRoot->m_pLeft!=nullptr)
            PrintTreeNode(pRoot->m_pLeft);

        if(pRoot->m_pRight!=nullptr)
            PrintTreeNode(pRoot->m_pRight);
    }
}

void DestroyTree(BinaryTreeNode* pRoot)
{
    if(pRoot!=nullptr)
    {
        BinaryTreeNode* pLeft=pRoot->m_pLeft;
        BinaryTreeNode* pRight=pRoot->m_pRight;

        delete pRoot;
        pRoot=nullptr;

        DestroyTree(pLeft);
        DestroyTree(pRight);
    }
}

bool Equal(const double &a,const double &b)
{
    if(fabs(a-b)<0.0000001)
        return true;
    return false;
}

bool DoesTreeAHaveTreeB(BinaryTreeNode* pRootA,BinaryTreeNode* pRootB)
{
    if(pRootB==nullptr)
        return true;
    if(pRootA==nullptr)
        return false;

    if(Equal(pRootA->m_Value,pRootB->m_Value))
    {
       return DoesTreeAHaveTreeB(pRootA->m_pLeft,pRootB->m_pLeft)&&DoesTreeAHaveTreeB(pRootA->m_pRight,pRootB->m_pRight);
    }
    else
    {
        return false;
    }
}
bool HasSubTree(BinaryTreeNode* pRootA,BinaryTreeNode* pRootB)
{
    if(pRootB==nullptr)
        return false;
    if(pRootA==nullptr)
        return false;

    bool result=false;

    if(Equal(pRootA->m_Value,pRootB->m_Value))
    {
        result=DoesTreeAHaveTreeB(pRootA,pRootB);
    }
    if(!result)
    {
        result=HasSubTree(pRootA->m_pLeft,pRootB);
    }
    if(!result)
    {
        result=HasSubTree(pRootA->m_pRight,pRootB);
    }

    return result;
}