《剑指offer》第二十八题（对称的二叉树）
作者：互联网
// 面试题28：对称的二叉树
// 题目：请实现一个函数，用来判断一棵二叉树是不是对称的。如果一棵二叉树和
// 它的镜像一样，那么它是对称的。
#include <iostream>
#include "List.h"
bool isSymmetrical(BinaryTreeNode* pRoot1, BinaryTreeNode* pRoot2);
bool isSymmetrical(BinaryTreeNode* pRoot)
{
return isSymmetrical(pRoot, pRoot);
}
bool isSymmetrical(BinaryTreeNode* pRoot1, BinaryTreeNode* pRoot2)
{
if (pRoot1 == nullptr && pRoot2 == nullptr)//当二者都为空，true
return true;
if (pRoot1 == nullptr || pRoot2 == nullptr)//只有一个为空，flase
return false;
if (pRoot1->m_nValue != pRoot2->m_nValue)//当二者值不等，flase
return false;
return isSymmetrical(pRoot1->m_pLeft, pRoot2->m_pRight)
&& isSymmetrical(pRoot1->m_pRight, pRoot2->m_pLeft);//看看你镜像和我是不是一样~
}//注意这里有个关键是，要测试是否都是空的，详见test9和10
// ====================测试代码====================
void Test(const char* testName, BinaryTreeNode* pRoot, bool expected)
{
if (testName != nullptr)
printf("%s begins: ", testName);
if (isSymmetrical(pRoot) == expected)
printf("Passed.\n");
else
printf("FAILED.\n");
}
// 8
// 6 6
// 5 7 7 5
void Test1()
{
BinaryTreeNode* pNode8 = CreateBinaryTreeNode(8);
BinaryTreeNode* pNode61 = CreateBinaryTreeNode(6);
BinaryTreeNode* pNode62 = CreateBinaryTreeNode(6);
BinaryTreeNode* pNode51 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode71 = CreateBinaryTreeNode(7);
BinaryTreeNode* pNode72 = CreateBinaryTreeNode(7);
BinaryTreeNode* pNode52 = CreateBinaryTreeNode(5);
ConnectTreeNodes(pNode8, pNode61, pNode62);
ConnectTreeNodes(pNode61, pNode51, pNode71);
ConnectTreeNodes(pNode62, pNode72, pNode52);
Test("Test1", pNode8, true);
DestroyTree(pNode8);
}
// 8
// 6 9
// 5 7 7 5
void Test2()
{
BinaryTreeNode* pNode8 = CreateBinaryTreeNode(8);
BinaryTreeNode* pNode61 = CreateBinaryTreeNode(6);
BinaryTreeNode* pNode9 = CreateBinaryTreeNode(9);
BinaryTreeNode* pNode51 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode71 = CreateBinaryTreeNode(7);
BinaryTreeNode* pNode72 = CreateBinaryTreeNode(7);
BinaryTreeNode* pNode52 = CreateBinaryTreeNode(5);
ConnectTreeNodes(pNode8, pNode61, pNode9);
ConnectTreeNodes(pNode61, pNode51, pNode71);
ConnectTreeNodes(pNode9, pNode72, pNode52);
Test("Test2", pNode8, false);
DestroyTree(pNode8);
}
// 8
// 6 6
// 5 7 7
void Test3()
{
BinaryTreeNode* pNode8 = CreateBinaryTreeNode(8);
BinaryTreeNode* pNode61 = CreateBinaryTreeNode(6);
BinaryTreeNode* pNode62 = CreateBinaryTreeNode(6);
BinaryTreeNode* pNode51 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode71 = CreateBinaryTreeNode(7);
BinaryTreeNode* pNode72 = CreateBinaryTreeNode(7);
ConnectTreeNodes(pNode8, pNode61, pNode62);
ConnectTreeNodes(pNode61, pNode51, pNode71);
ConnectTreeNodes(pNode62, pNode72, nullptr);
Test("Test3", pNode8, false);
DestroyTree(pNode8);
}
// 5
// / \
// 3 3
// / \
// 4 4
// / \
// 2 2
// / \
// 1 1
void Test4()
{
BinaryTreeNode* pNode5 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode31 = CreateBinaryTreeNode(3);
BinaryTreeNode* pNode32 = CreateBinaryTreeNode(3);
BinaryTreeNode* pNode41 = CreateBinaryTreeNode(4);
BinaryTreeNode* pNode42 = CreateBinaryTreeNode(4);
BinaryTreeNode* pNode21 = CreateBinaryTreeNode(2);
BinaryTreeNode* pNode22 = CreateBinaryTreeNode(2);
BinaryTreeNode* pNode11 = CreateBinaryTreeNode(1);
BinaryTreeNode* pNode12 = CreateBinaryTreeNode(1);
ConnectTreeNodes(pNode5, pNode31, pNode32);
ConnectTreeNodes(pNode31, pNode41, nullptr);
ConnectTreeNodes(pNode32, nullptr, pNode42);
ConnectTreeNodes(pNode41, pNode21, nullptr);
ConnectTreeNodes(pNode42, nullptr, pNode22);
ConnectTreeNodes(pNode21, pNode11, nullptr);
ConnectTreeNodes(pNode22, nullptr, pNode12);
Test("Test4", pNode5, true);
DestroyTree(pNode5);
}
// 5
// / \
// 3 3
// / \
// 4 4
// / \
// 6 2
// / \
// 1 1
void Test5()
{
BinaryTreeNode* pNode5 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode31 = CreateBinaryTreeNode(3);
BinaryTreeNode* pNode32 = CreateBinaryTreeNode(3);
BinaryTreeNode* pNode41 = CreateBinaryTreeNode(4);
BinaryTreeNode* pNode42 = CreateBinaryTreeNode(4);
BinaryTreeNode* pNode6 = CreateBinaryTreeNode(6);
BinaryTreeNode* pNode22 = CreateBinaryTreeNode(2);
BinaryTreeNode* pNode11 = CreateBinaryTreeNode(1);
BinaryTreeNode* pNode12 = CreateBinaryTreeNode(1);
ConnectTreeNodes(pNode5, pNode31, pNode32);
ConnectTreeNodes(pNode31, pNode41, nullptr);
ConnectTreeNodes(pNode32, nullptr, pNode42);
ConnectTreeNodes(pNode41, pNode6, nullptr);
ConnectTreeNodes(pNode42, nullptr, pNode22);
ConnectTreeNodes(pNode6, pNode11, nullptr);
ConnectTreeNodes(pNode22, nullptr, pNode12);
Test("Test5", pNode5, false);
DestroyTree(pNode5);
}
// 5
// / \
// 3 3
// / \
// 4 4
// / \
// 2 2
// \
// 1
void Test6()
{
BinaryTreeNode* pNode5 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode31 = CreateBinaryTreeNode(3);
BinaryTreeNode* pNode32 = CreateBinaryTreeNode(3);
BinaryTreeNode* pNode41 = CreateBinaryTreeNode(4);
BinaryTreeNode* pNode42 = CreateBinaryTreeNode(4);
BinaryTreeNode* pNode21 = CreateBinaryTreeNode(2);
BinaryTreeNode* pNode22 = CreateBinaryTreeNode(2);
BinaryTreeNode* pNode12 = CreateBinaryTreeNode(1);
ConnectTreeNodes(pNode5, pNode31, pNode32);
ConnectTreeNodes(pNode31, pNode41, nullptr);
ConnectTreeNodes(pNode32, nullptr, pNode42);
ConnectTreeNodes(pNode41, pNode21, nullptr);
ConnectTreeNodes(pNode42, nullptr, pNode22);
ConnectTreeNodes(pNode21, nullptr, nullptr);
ConnectTreeNodes(pNode22, nullptr, pNode12);
Test("Test6", pNode5, false);
DestroyTree(pNode5);
}
// 只有一个结点
void Test7()
{
BinaryTreeNode* pNode1 = CreateBinaryTreeNode(1);
Test("Test7", pNode1, true);
DestroyTree(pNode1);
}
// 没有结点
void Test8()
{
Test("Test8", nullptr, true);
}
// 所有结点都有相同的值，树对称
// 5
// / \
// 5 5
// / \
// 5 5
// / \
// 5 5
void Test9()
{
BinaryTreeNode* pNode1 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode21 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode22 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode31 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode32 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode41 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode42 = CreateBinaryTreeNode(5);
ConnectTreeNodes(pNode1, pNode21, pNode22);
ConnectTreeNodes(pNode21, pNode31, nullptr);
ConnectTreeNodes(pNode22, nullptr, pNode32);
ConnectTreeNodes(pNode31, pNode41, nullptr);
ConnectTreeNodes(pNode32, nullptr, pNode42);
ConnectTreeNodes(pNode41, nullptr, nullptr);
ConnectTreeNodes(pNode42, nullptr, nullptr);
Test("Test9", pNode1, true);
DestroyTree(pNode1);
}
// 所有结点都有相同的值，树不对称
// 5
// / \
// 5 5
// / \
// 5 5
// / /
// 5 5
void Test10()
{
BinaryTreeNode* pNode1 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode21 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode22 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode31 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode32 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode41 = CreateBinaryTreeNode(5);
BinaryTreeNode* pNode42 = CreateBinaryTreeNode(5);
ConnectTreeNodes(pNode1, pNode21, pNode22);
ConnectTreeNodes(pNode21, pNode31, nullptr);
ConnectTreeNodes(pNode22, nullptr, pNode32);
ConnectTreeNodes(pNode31, pNode41, nullptr);
ConnectTreeNodes(pNode32, pNode42, nullptr);
ConnectTreeNodes(pNode41, nullptr, nullptr);
ConnectTreeNodes(pNode42, nullptr, nullptr);
Test("Test10", pNode1, false);
DestroyTree(pNode1);
}
void main(int argc, char* argv[])
{
Test1();
Test2();
Test3();
Test4();
Test5();
Test6();
Test7();
Test8();
Test9();
Test10();
system("pause");
}
标签：第二十八,ConnectTreeNodes,offer,nullptr,CreateBinaryTreeNode,BinaryTreeNode,二叉树,pNod 来源： https://www.cnblogs.com/CJT-blog/p/10491586.html