This article will introduce how to manage multiple ruby versions on the same computer. Here I use uru for windows and RVM for Ubuntu as examples. uru and RVM uru is the tool that could manage multiple ruby versions (https://bitbucket.org/jonforums/uru/src/master/). We can use it in Windows. RVM is the tool that most people…

This article introduces how to solve the error when installing mysql2 gem with ruby 3.1 and rails 7.0. Before you start, please check whether you already installed the MySQL connector. Error while installing mysql2 with ruby 3.1 I am not sure what the root cause is. I encountered an issue while switching from ruby 2.6.8 to ruby…

In this article, I will introduce how to use logistic regression in python. As we know, logistic regression can be used for classification problems. For the binary classification, we will get the probabilities to class ‘0’ and to class ‘1’. …

In this article, I will introduce how to use DP and double-ended queue to solve the LeetCode #1696, Jump Game VI. Question: Given an integer array nums and an integer k. We can jump between 1 step and k steps. Each value in the nums array is a score. We want…

LeetCode #39, Combination Sum, is a classical backtracking problem. This question is, given an input array with unique numbers called candidates, and an integer called target. We need to find all possible combinations of numbers from candidates that the sum of the numbers in each combination equals to the target. …

In this article, I will introduce LeetCode #484, find permutation. The question is given a string that contains the combination of ‘I’ and ‘D’. These two characters mean the following two conditions: # s is input string, i is the index of character # output is the final results c = s[i] If…

This article will talk about how to use backtracking to solve Leetcode #47, Permutations II. This problem is similar to #46, Permutations. The only difference is that the numbers are not unique in this problem. …

In this article, I will introduce how to use the pem file in MobaXterm to connect the ec2 machine in AWS, and how I solve the issue I encountered when I use the pem file generated by AWS for the private key. First of all, go to the session settings…