Day 15 年三十

今天太忙了…
一、理论学习

二、刷题学习

104. 二叉树的最大深度

应该确实比以前有提升了 已经能写出这么精简的代码了

/*** 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:int maxDepth(TreeNode* root) {if(root==nullptr) return 0;return 1+max(maxDepth(root->left),maxDepth(root->right));}
};

111. 二叉树的最小深度

/*** 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:int minDepth(TreeNode* root) {if (root == NULL) return 0;if (root->left == NULL && root->right != NULL) {return 1 + minDepth(root->right);}if (root->left != NULL && root->right == NULL) {return 1 + minDepth(root->left);}return 1 + min(minDepth(root->left), minDepth(root->right));}
};

222. 完全二叉树的节点个数

自己尝试

/*** 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:int nums(TreeNode* root,int num){if(root==nullptr) return 0;num=num+1;int left=nums(root->left,num);int right=nums(root->right,num);return left+right+1;}int countNodes(TreeNode* root) {return nums(root,0);}
};

三、新年快乐