代码随想录Day14_

226. 翻转二叉树 - 力扣（LeetCode）

class Solution {
public:TreeNode* invertTree(TreeNode* root) {if(root==NULL) return root;swap(root->left,root->right);invertTree(root->left);invertTree(root->right);return root;}
};

101. 对称二叉树 - 力扣（LeetCode）

class Solution {
public:bool isSymmetric(TreeNode* root) {if (root == NULL)return true;return compare(root->left, root->right);}bool compare(TreeNode* left, TreeNode* right) {if (left == NULL && right != NULL)return false;if (left != NULL && right == NULL)return false;if (left == NULL && right == NULL)return true;if (left->val != right->val)return false;else {bool outside = compare(left->left, right->right);bool Inside = compare(left->right, right->left);return outside && Inside;}}
};

104. 二叉树的最大深度 - 力扣（LeetCode）

为什么要引出高度呢？

class Solution {
public:int GetHi(TreeNode* node){if(node==NULL) return 0;else return 1+max(GetHi(node->left),GetHi(node->right));}int maxDepth(TreeNode* root) {return GetHi(root);}
};

111. 二叉树的最小深度 - 力扣（LeetCode）