1. 题目
请实现一个函数，用来判断一棵二叉树是不是对称的：如果一颗二叉树和它的镜像一样，那么它是对称的。
2. 解析
两层节点：对称的情况分析
两个父节点的值对称（相等）
左父节点的左子节点与右父节点的右子节点对称
左父节点的右子节点与右父节点的左子节点对称
第三层节点：采用递归
根节点：根节点作为两个父节点进行输入
3. 参考
- SymmetricalBinaryTree.cpp
include <cstdio>#include "../Utilities/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) return true; if(pRoot1 == nullptr || pRoot2 == nullptr) return false; if(pRoot1->m_nValue != pRoot2->m_nValue) return false; return isSymmetrical(pRoot1->m_pLeft, pRoot2->m_pRight) && isSymmetrical(pRoot1->m_pRight, pRoot2->m_pLeft);}- BinaryTree.cpp
#include <cstdio>#include "BinaryTree.h"BinaryTreeNode* CreateBinaryTreeNode(int value){ BinaryTreeNode* pNode = new BinaryTreeNode(); pNode->m_nValue = value; 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 PrintTreeNode(const BinaryTreeNode* pNode){ if(pNode != nullptr) { printf("value of this node is: %d
", pNode->m_nValue); if(pNode->m_pLeft != nullptr) printf("value of its left child is: %d.
", pNode->m_pLeft->m_nValue); else printf("left child is nullptr.
"); if(pNode->m_pRight != nullptr) printf("value of its right child is: %d.
", pNode->m_pRight->m_nValue); else printf("right child is nullptr.
"); } else { printf("this node is nullptr.
"); } printf("
");}void PrintTree(const BinaryTreeNode* pRoot){ PrintTreeNode(pRoot); if(pRoot != nullptr) { if(pRoot->m_pLeft != nullptr) PrintTree(pRoot->m_pLeft); if(pRoot->m_pRight != nullptr) PrintTree(pRoot->m_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); }}作者：陈满iOS
iOS开发整理发布，转载请联系作者获得授权
（其实做为一个开发者，有一个学习的氛围跟一个交流圈子特别重要，这是一个我的iOS学习交流群687528266，不管你是小白还是大牛欢迎入驻，大家一起交流学习）