SubstructureInTree.cpp

// 面试题26：树的子结构
// 题目：输入两棵二叉树A和B，判断B是不是A的子结构。

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


bool DoesTree1HaveTree2(BinaryTreeNode* pRoot1, BinaryTreeNode* pRoot2);
bool Equal(double num1, double num2);

bool HasSubtree(BinaryTreeNode* pRoot1, BinaryTreeNode* pRoot2)
{
    bool result = false;

    if(pRoot1 != nullptr && pRoot2 != nullptr)
    {
        if(Equal(pRoot1->m_dbValue, pRoot2->m_dbValue))
            result = DoesTree1HaveTree2(pRoot1, pRoot2);
        if(!result)
            result = HasSubtree(pRoot1->m_pLeft, pRoot2);
        if(!result)
            result = HasSubtree(pRoot1->m_pRight, pRoot2);
    }

    return result;
}

bool DoesTree1HaveTree2(BinaryTreeNode* pRoot1, BinaryTreeNode* pRoot2)
{
    if(pRoot2 == nullptr)
        return true;

    if(pRoot1 == nullptr)
        return false;

    if(!Equal(pRoot1->m_dbValue, pRoot2->m_dbValue))
        return false;

    return DoesTree1HaveTree2(pRoot1->m_pLeft, pRoot2->m_pLeft) &&
        DoesTree1HaveTree2(pRoot1->m_pRight, pRoot2->m_pRight);
}

bool Equal(double num1, double num2)
{
    if((num1 - num2 > -0.0000001) && (num1 - num2 < 0.0000001))
        return true;
    else
        return false;
}