Michael's Blog

How to install Swift and Vapor on Ubuntu 20.04

This blog post just talk about how to install Swift and Vapor on Ubuntu 20.04. Let's install Swift first, Install some dependencies including clang and Python components sudo apt install clang libpython2.7 libpython2.7-dev 2. Download Swift for Ubuntu 20.04 from [Download Swift](https://www.swift.org/

SwiftUI

How to create Tab Bar using TabView in SwiftUI

In UIKit, we use the UITabBarController to create the tab bar. While in SwiftUI we could use TabView instead. To create a user interface with tabs, we place views in a TabView and apply the tabItem(_:) modifier to the contents of each tab. Here is an example, struct ProjectView: View

How to increase storage of Android Emulator

I came across the INSTALL_FAILED_INSUFFICIENT_STORAGE error when I tried to install my app on the Android emulator. I found out that the storage of my Android emulator has run out. I have tried to update the Internal Storage of AVD directly but it did not work for

Upgrade blog from Ghost 0.11 to 4.x

Previously this blog is using a pretty old version of Ghost 0.11, which was released back in 2016 and the tool Ghost-CLI was not released yet. This blog is hosting on the DigitalOcean using Ubuntu 14.04, so I decided to migrate it to a new Droplet with Ubuntu

Tesla

关于特斯拉4680电池

在2020年9月举办的特斯拉电池日上，特斯拉公布了自产新型4680电池的一些细节，与2170电池一样同样是圆柱形结构，但明显体积要大了不少，高度达到80MM, 直径达到46MM。相比现在特斯拉使用的2170电芯，4680电芯容量上提升5倍，输出功率提高6倍，整车续航里程也将增加16%。新电池内部还采用了无极耳设计，有助于降低内阻，减少发热，从而为车辆带来更优秀的能耗表现以及充电性能。使用4680电芯和新结构化的电池包(structural battery pack)之后，一台车上的电池外壳材料将会减少，使得制造成本进一步降低，每kWh的电池成本降低56%，每kWh所需的投资成本降低69%。在2021第四季度财报会议上，特斯拉更新了一些关于4680电池的消息。自从揭晓了4680电池后，特斯拉一直在加州的弗里蒙特(Fremont)工厂小量的试生产，然后计划在德州(Gigafactory Texas)和柏林(Gigafactory Berlin)超级工厂大规模量产4680电池。目前在Fremont的4680电池产能正在爬坡，预计年产能将达10GWh。德州超级工厂将会是第一个大规模量产4680电池的工厂，预计年产能达到100GWh。最近松下也宣布开始试生产4680电池，预计2023年优先供货特斯拉。特斯拉一直没有透露2022年4680电池具体的产能是多少，但特斯拉的工程部高级副总Drew Baglino提到电池不会是一个瓶颈，而芯片短缺仍然会是一个瓶颈。同时这哥们透露已经开了几天装配4680电池的Model Y，让人羡慕！德州超级工厂已经小批量生产了装配4680电池和新结构化电池包的Model

Swift

How to implement Stack in Swift

A stack is a last-in-first-out (LIFO) collection, which means the last thing we pushed is the first thing that gets popped off. If you used UINavigationController before, probably you used the method pushViewController(_:animated:) to push a view controller onto the navigation stack, and then used method popViewController(animated:) to

iOS

How to use NSCache in Swift

NSCache is a mutable dictionary that you could use to cache some data that are expensive to create, so it could improve your app performance. If memory is needed by other applications, it would remove some items from the cache, minimizing its memory footprint, then some values need to be

iOS

How to implement recursiveDescription method in Swift

You might find out that the private method of UIView recursiveDescription is useful, especially when you want to debug your view hierarchy. You could run the following command from the LLDB prompt in Xcode: po view.value(forKey: "recursiveDescription")! It would print the view hierarchy for you, all

iOS

How to scroll UITableView to the top

There is an instance method of UIScrollView called setContentOffset(_:animated:). As UITableView is a subclass of UIScrollView, you could also use this method. If you need to scroll the table view to the top, you just call this method like below: tableView.setContentOffset(.zero, animated: true) Hope this helps, Michael

LeetCode

Word Break II

140. Word Break II Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, add spaces in s to construct a sentence where each word is a valid dictionary word. You may assume the dictionary does not contain duplicate words. Return all such possible sentences.

Array

Rotate Image

48. Rotate Image You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Follow up: Could you do this in-place? public class Solution { public void rotate(int[][] matrix) { if (matrix == null) { return; } int n = matrix.length; for (int i = 0; i

Hash Table

Valid Sudoku

36. Valid Sudoku Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules. The Sudoku board could be partially filled, where empty cells are filled with the character '.'. Note: A valid Sudoku board (partially filled) is not necessarily solvable. Only the filled cells need to

Array

Search Insert Position

35. Search Insert Position Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order. You may assume no duplicates in the array. Here are few examples. [1,3,5,

LeetCode

Reverse Nodes in k-Group

25. Reverse Nodes in k-Group Given a linked list, reverse the nodes of a linked list k at a time and return its modified list. If the number of nodes is not a multiple of k then left-out nodes in the end should remain as it is. You may not

Regular Expression Matching

10. Regular Expression Matching Implement regular expression matching with support for '.' and '*'. '.' Matches any single character. '*' Matches zero or more of the preceding element. The matching should cover the entire input string (not partial). The function prototype should be: bool isMatch(const

LeetCode

ZigZag Conversion

6. ZigZag Conversion The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility) P A H N A P L S I I G Y I R

LeetCode

Longest Palindromic Substring

5. Longest Palindromic Substring Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. Example: Input: "babad" Output: "bab" Note: "aba" is also a valid answer. Example: Input: "cbbd" Output:

LeetCode

Median of Two Sorted Arrays

4. Median of Two Sorted Arrays There are two sorted arrays nums1 and nums2 of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)). Example 1: nums1 = [1, 3] nums2 = [2] The median is 2.

LeetCode

Number of Connected Components in an Undirected Graph

323. Number of Connected Components in an Undirected Graph Given n nodes labeled from 0 to n - 1 and a list of undirected edges (each edge is a pair of nodes), write a function to find the number of connected components in an undirected graph. Example 1: 0 3

LeetCode

Linked List Random Node

382. Linked List Random Node Given a singly linked list, return a random node's value from the linked list. Each node must have the same probability of being chosen. Follow up: What if the linked list is extremely large and its length is unknown to you? Could you solve this

LintCode

First Position of Target

LintCode-14.First Position of Target For a given sorted array (ascending order) and a target number, find the first index of this number in O(log n) time complexity. If the target number does not exist in the array, return -1. Example If the array is [1, 2, 3, 3,

LintCode

Find Minimum in Rotated Sorted Array II

LintCode-160.Find Minimum in Rotated Sorted Array II Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2). Find the minimum element. Notice The array may contain duplicates. Example

iOS

Swift 3 Migration Issues

As you already know that Swift 3 is released, I guess you guys are busy migrating your project to Swift 3 now. So this post I just list some issues I came across during migrating to Swift 3. 1.Instance method 'application(:didFinishLaunchingWithOptions:)' nearly matches optional requirement 'application(:didFinishLaunchingWithOptions:

LintCode

Remove Duplicates from Unsorted List

LintCode-217.Remove Duplicates from Unsorted List Write code to remove duplicates from an unsorted linked list. Example Given 1->3->2->1->4. Return 1->3->2->4 Challenge (hard) How would you solve this problem if a temporary buffer is not allowed?

LintCode

Longest Words

LintCode-133.Longest Words Given a dictionary, find all of the longest words in the dictionary. Example Given { "dog", "google", "facebook", "internationalization", "blabla" } the longest words are(is) ["internationalization"]. Given { "like", "love", "hate"