// 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 "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，truereturn true;if (pRoot1 == nullptr || pRoot2 == nullptr)//只有一个为空，flasereturn false;if (pRoot1->m_nValue != pRoot2->m_nValue)//当二者值不等，flasereturn 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");elseprintf("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");
}