// 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#include "BinaryTree.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 5void 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 5void 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 7void 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 1void 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 1void 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// \// 1void 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 5void 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 5void 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");}