剑指offer--面试题26：树的子结构

#include <stdio.h>
#define nullptr NULL
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;
}

BinaryTreeNode* CreateBinaryTreeNode(double dbValue)
{
BinaryTreeNode* pNode = new BinaryTreeNode();
pNode->m_dbValue = dbValue;
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 DestroyTree(BinaryTreeNode* pRoot)
{
if(pRoot != nullptr)
{
BinaryTreeNode* pLeft = pRoot->m_pLeft;
BinaryTreeNode* pRight = pRoot->m_pRight;

delete pRoot;
pRoot = nullptr;

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

// 树中结点含有分叉，树B是树A的子结构
//                  8                8
//              /       \           / \
//             8         7         9   2
//           /   \
//          9     2
//               / \
//              4   7

int main()
{
BinaryTreeNode* pNodeA1 = CreateBinaryTreeNode(8);
BinaryTreeNode* pNodeA2 = CreateBinaryTreeNode(8);
BinaryTreeNode* pNodeA3 = CreateBinaryTreeNode(7);
BinaryTreeNode* pNodeA4 = CreateBinaryTreeNode(9);
BinaryTreeNode* pNodeA5 = CreateBinaryTreeNode(2);
BinaryTreeNode* pNodeA6 = CreateBinaryTreeNode(4);
BinaryTreeNode* pNodeA7 = CreateBinaryTreeNode(7);

ConnectTreeNodes(pNodeA1, pNodeA2, pNodeA3);
ConnectTreeNodes(pNodeA2, pNodeA4, pNodeA5);
ConnectTreeNodes(pNodeA5, pNodeA6, pNodeA7);

BinaryTreeNode* pNodeB1 = CreateBinaryTreeNode(8);
BinaryTreeNode* pNodeB2 = CreateBinaryTreeNode(9);
BinaryTreeNode* pNodeB3 = CreateBinaryTreeNode(2);

ConnectTreeNodes(pNodeB1, pNodeB2, pNodeB3);

if(HasSubtree(pNodeA1, pNodeB1))

printf("树2是树1的子树\n");

DestroyTree(pNodeA1);
DestroyTree(pNodeB1);
return 0;
}