镜像二叉树

Posted 2021-07-17 编程der艺术

给定一个二叉树，检查它是否是镜像对称的。

例如，二叉树 [1,2,2,3,4,4,3] 是对称的。

    1
   / \
  2   2
 / \ / \
3  4 4  3

/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode() : val(0), left(nullptr), right(nullptr) {} * TreeNode(int x) : val(x), left(nullptr), right(nullptr) {} * TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {} * }; */class Solution {public: bool isSymmetric(TreeNode* root) { //中左右 == 中右左 stack<TreeNode*> stkLeftFirst,stkRightFirst; stkLeftFirst.push(root); stkRightFirst.push(root); bool res = true; TreeNode *leftNode, *rightNode; while(!stkLeftFirst.empty()&&!stkRightFirst.empty()) { leftNode = stkLeftFirst.top(); stkLeftFirst.pop(); rightNode = stkRightFirst.top(); stkRightFirst.pop(); res = res &  leftNode == nullptr ? rightNode == nullptr :  (rightNode != nullptr)&&(leftNode->val == rightNode->val); if(!res)return res; if(leftNode != nullptr && rightNode != nullptr) { stkLeftFirst.push(leftNode->right); stkLeftFirst.push(leftNode->left); stkRightFirst.push(rightNode->left); stkRightFirst.push(rightNode->right); } } return res; }};