Serena Chen-优快云博客

原创《Machine Learning A-Z》Part 2 - Regression Models Selection and Evaluation

Performance of Regression Models1. Simple Linear Regression :SSres = SUM(yi - yi^)^2 -> minSStot = SUM(yi - y_avg)^2 -> minR^2 = 1 - SSres/SStot (from 0 to 1)R^2 is the Goodness of fit. (The closer R^2 closer to 1, the better the performan.

2021-08-21 00:50:32 243

原创《Machine Learning A-Z》Part 2 (6) - Random Forest Regression

12.08.2021Random Forest RegressionRandom Forest Learning is a version of Ensemble Learning, there are also other version such as gradient boosting. Ensemble Learning is you take multiple algorithms or an algorithm multiple times and you put them togeth

2021-08-12 23:59:18 247

原创《Machine Learning A-Z》Part 2 (5) - Decision Tree Regression

11.08.2021Decision Tree RegressionTo know deeper about it, we need to learn about Information entropy to have a mathematical insight intoit. But the whole of this algorithm is to add more information into our system to achieve better prediction. If .

2021-08-12 22:15:10 228

原创 LeetCode - Valid Palindrome II

11.08.2021小白一枚，文章仅当日记本记录学习进度 ;)如被浏览，请多多指教，非常感谢大家纠错与建议！（因留学顺便练习英语，所以部分用英文笔记，并无他意）Solution - Two pointers (Python)class Solution: def validPalindrome(self, s: str) -> bool: left = 0 right = len(s) - 1 while left &lt.

2021-08-12 01:51:02 141

原创《Machine Learning A-Z》Part 2 (4) - Support Vector Regression(SVR)

06.08.202106.08.2021Part 2 Regression(4) Support Vector Regression (SVR)支持向量回归涉及到的一个非常重要的方法：最小二乘法（Ordinary Least Squares)--> minThe least squares method is a statistical procedure to find the best fit for a set of data points by minimizi..

2021-08-09 01:23:54 220

原创 LeetCode - Dot Product of Two Sparse Vector

07.08.2021Approach 1 -Non-efficient Array Approach

2021-08-08 20:52:53 255

原创《Machine Learning A-Z》Part 2 (3) - Polynomial Linear Regression

05.08.202106.08.202106.08.2021Part 2 Regression(2) PolynomialLinear RegressionQ：为什么Polynomial function，但依然可以被称为linear regression呢？(A polynomial function is a function such as a quadratic, a cubic, a quartic, and so on, involving only non-negat.

2021-08-07 00:44:27 188

原创《Machine Learning A-Z》- Part 2 (1) - Simple Linear Regression

05.08.2021Part 2 Regression(1) Simple Linear RegressionRegression models (both linear or non-linear) are used to predict a real continuous value (like salary), if your independent variable is time, then you are forecasting the future values..

2021-08-06 04:54:23 307

原创《Machine Learning A-Z》- Part 2 (2) - Multiple Linear Regression

05.08.2021Part 2 Regression(1) Simple Linear RegressionRegression models (both linear or non-linear) are used to predict a real continuous value (like salary), if your independent variable is time, then you are forecasting the future values..

2021-08-06 04:53:13 526

原创 LeetCode - Verifying an Alien Dictionary

04.08.2021小白一枚，文章仅当日记本记录学习进度 ;)如被浏览，请多多指教，非常感谢大家纠错与建议！（因留学顺便练习英语，所以部分用英文笔记，并无他意）This is Facebook most asked questionin 2020 and 2021, this is a sub-task of another Hard problem 'Alien Dictionary' which is much simpler. (ps: 一位YouTuber是这样说的但是我真的花了..

2021-08-05 06:10:48 197

原创《Machine Learning A-Z》- Part 1 - Data Processing

03.08.2021暑假期间充分利用时间，买了Udemy上的 Machine Learning A-Z 课程，在此记录一下学习内容;)Part 0IntroductionIntroductionIntroduced vast applications of Machine Learning. For example, face recognition, voice recognition, Virtual Reality, Robot Dogs learn how to walk..

2021-08-05 03:12:19 206

原创《Machine Learning A-Z》- Part 0 - Welcome to Machine Learning

03.08.2021暑假期间充分利用时间，买了Udemy上的 Machine Learning A-Z 课程，在此记录一下学习内容;)Part 0IntroductionIntroductionIntroduced vast applications of Machine Learning. For example, face recognition, voice recognition, Virtual Reality, Robot Dogs learn how to walk..

2021-08-05 03:10:49 241

原创 LeetCode - Merge Intervals

02.08.2021小白一枚，文章仅当日记本记录学习进度 ;)如被浏览，请多多指教，非常感谢大家纠错与建议！（因留学顺便练习英语，所以部分用英文笔记，并无他意）Solution 1 - sort it first (Python)Time complexity is O(nlogn)， Space complexity is O(n)1. Sort the list by the first element2. Iterate intervals and do the l..

2021-08-03 03:36:41 322

原创 LeetCode - LRU Cache

01.08.2021小白一枚，文章仅当日记本记录学习进度 ;)如被浏览，请多多指教，非常感谢大家纠错与建议！（因留学顺便练习英语，所以部分用英文笔记，并无他意）cache : inmemory that holds the most recent result; LRU is a common cache algorithm1. When you see put and get, you shold think of Hashmap immediately which hasi...

2021-08-02 21:41:13 171

原创 LeetCode - Candy

25.07.2021小白一枚，文章仅当日记本记录学习进度 ;)如被浏览，请多多指教，非常感谢大家纠错与建议！（因留学顺便练习英语，所以部分用英文笔记，并无他意）Solution - Greedy algorithm (Java)We can use the greedy algorithm strategy to solve this problem by only considering the relationship of neighbors.1. Initializin.

2021-07-26 04:49:30 205

原创 LeetCode - Assign Cookies

25.07.2021小白一枚，文章仅当日记本记录学习进度 ;)如被浏览，请多多指教，非常感谢大家纠错与建议！（因留学顺便练习英语，所以部分用英文笔记，并无他意）class Solution { public int findContentChildren(int[] g, int[] s) { Arrays.sort(g); Arrays.sort(s); int child = 0, cookie = 0; w.

2021-07-26 00:03:19 108

原创 LeetCode - Palindrome Number

24.07.2021小白一枚，文章仅当日记本记录学习进度 ;)如被浏览，请多多指教，非常感谢大家纠错与建议！（因留学顺便练习英语，所以用英文笔记，并无他意）- Could you solve it without converting the integer to a string?Solution 1 - reverse the number (Java)Runtime:7 ms, faster than69.75%ofJavaonline submissions ...

2021-07-25 05:04:08 285

原创 LeetCode - Reverse Integer

24.07.2021小白一枚，文章仅当日记本记录学习进度 ;)如被浏览，请多多指教，非常感谢大家纠错与建议！（因留学顺便练习英语，所以用英文笔记，并无他意）Solution 1 - Pythonstep1: Assume we are dealing with an environment which could only stores integers within the 32-bits signed integer range. - Assume the funciton r.

2021-07-25 03:00:45 282 2

原创 LeetCode - Two Sum

23.07.2021小白一枚，文章仅当日记本记录学习进度 ;)如被浏览，请多多指教，感谢大家纠错与建议????（因留学顺便练习英语，所以用英文笔记，并无他意）1.Two SumSolution 0 - 2 for loops (Java)class Solution { public int[] twoSum(int[] nums, int target) { for (int i = 0; i < nums.length ; i++) {

2021-07-24 04:15:01 363 1

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