LouisLan的学习简记 👋🏼

? ## ? 基于神经网络的降雨预测 占坑学习，以后再理解，脑壳痛！ 源数据：tianjin.xlsx python代码： import numpy as np import pandas as pd import sklearn filename = r'tianjin.xlsx' data = pd.read_excel(filename) pd.set_option('display.max_columns',None) # data.head() # data = data.drop('ET0',axis=1)#去除数据集中的ET0 data.head() # 读取前五行数据 len(data) len(data.columns) print(len(data.columns)) data = data.drop(['PMax','ET0', 'Rn', 'Wind', 'PMean', 'TMean', 'Delta','Gama'],axis = 1)#去除不需要的参数 print(data) #data = data.drop(['PMax', 'Wind', 'PMin....

题目地址 https://leetcode.com/problems/balanced-binary-tree/ 题目描述 Given a binary tree, determine if it is height-balanced. For this problem, a height-balanced binary tree is defined as: a binary tree in which the depth of the two subtrees of every node never differ by more than 1. Example 1: Given the following tree [3,9,20,null,null,15,7]: 3 / \ 9 20 / \ 15 7 Return true. Example 2: Given the following tree [1,2,2,3,3,null,null,4,4]: 1 / \ 2 2 / \ 3 3 / \ 4 4 Return false. 思路 求二叉树是否平衡，根据题目中的定....

题目地址 https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree/ 题目描述 Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST. For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1. Example: Given the sorted linked list: [-10,-3,0,5,9], One possible answer is: [0,-3,9,-10,null,5], which represents the following height balanced BS....

题目地址 https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/ 题目描述 Given an array where elements are sorted in ascending order, convert it to a height balanced BST. For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1. Example: Given the sorted array: [-10,-3,0,5,9], One possible answer is: [0,-3,9,-10,null,5], which represents the following height balanced BST: 0 / \ -3 9 / /....

题目地址 https://leetcode.com/problems/binary-tree-level-order-traversal-ii/ 题目描述 Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root). For example: Given binary tree {3,9,20,#,#,15,7}, 3 / \ 9 20 / \ 15 7 return its bottom-up level order traversal as: [ [15,7], [9,20], [3] ] 思路 从底部层序遍历其实还是从顶部开始遍历，只不过最后存储的方式有所改变，可以参见我之前的博文 Binary Tree Level Order Traversal 关键点解析 代码 解法一： class Solution { public: vector<v....

题目地址 https://leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal/ 题目描述 Given inorder and postorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tree. 思路 这道题要求从中序和后序遍历的结果来重建原二叉树，我们知道中序的遍历顺序是左-根-右，后序的顺序是左-右-根，对于这种树的重建一般都是采用递归来做，可参见我之前的一篇博客Convert Sorted Array to Binary Search Tree 将有序数组转为二叉搜索树。针对这道题，由于后序的顺序的最后一个肯定是根，所以原二叉树的根节点可以知道，题目中给了一个很关键的条件就是树中没有相同元素，有了这个条件我们就可以在中序遍历中也定位出根节点的位置，并以根节点的位置将中序遍历拆分为左右两个部分，分别对其递....