Attention: This post was updated to include the alternate solution that uses binary search. It reduces the Time Complexity from O(n * n) to O(n * log n). Before we present the question. Let’s figure out what a subsequence is: What’s a subsequence? Any selection of items from the original array. The selection must respect the order. Meaning for [1,2,3,4,5] only two of the four below are subsequences: [1,2,3,4,5] ✅ [1,4,3,2,5] ❌ order not respected [1,2,5] ✅ [5,1] ❌ order not respected What’s the difference between a subsequence and a subarray?...

This is the 1st post of “Everything I learned from blogging with Hugo” series I started blogging in Dec 2021. It’s been a wonderful journey. Has enabled me to gather my thoughts in a far more structured way. The series is based on my setup of Hugo - Netlify - GitHub. I’ll shared my knowledge in terms of Hugo knowledge, how to write a blog post and more. If anyone is interested in the Netlify setup, see Hugo Quick Start then Netlify - Hugo setup....

I do leetcoding every once a while, but keep forgetting some tree basics. This post here it to help with that. Types of Tree Trees can have multiple children. Or on the special case of binary trees have only two. A binary tree is still different from a binary search tree (BST) where things follow a certain order. Binary search tree For a Binary tree to be a BST, it has to follow the following rules:...

In the previous posts we talked about Build Pipeline, Jargon, Static Linker vs Dynamic Linker. In this post we’ll benefit from the knowledge gained about the app wrapper’s folder structure and the placement of all the different binaries (frameworks and main app’s executable) to know where to look for. New in this post is learning how to use the nm command to inspect and count the number of symbols of each binary....

In the previous post we talked about how the linker’s selective loading helps solve the bloat issue. But there are some other limitations to static linking. Because of those limitations software engineers created Dynamic libraries and the Dynamic Linker. In this post we’ll go through some of those limitations and discuss the trade-offs between the two ways of linking and their sizing impact. Inspired by Link fast: Improve build and launch times - 15:47:...

In the previous post we talked about a problem with the linker: Linking a single function from a library could link to the entire library. This creates a lot of bloat. As a result some enhancements were made to linker. The enhancement was to be selective and only load symbols that you need. Inspired by Link fast: Improve build and launch times - 4:15: Selective Loading In a nutshell if you have the following source code written in C:...

To understand this post, I highly recommend everyone to watch the WWDC 2022 - Link fast: Improve build and launch times and WWDC 2018 - Behind the Scenes of the Xcode Build Process. They’re of the best talks I’ve ever seen. This post covers some of the jargon and how it all comes together. And even though I love making puzzles, I’ll justify why I picked it as my cover....

This the first post of a series I’m doing on how to optimize your app’s binaries. The post is more of a high level intro. Depending on the action (build, run, test, profile, analyze, archive) of your scheme, the process will have all or some of the following steps: Dependency analysis What happens when you press build? So the first step is for the build system to take the build description, your Xcode project file....

A binary is the final product from linking all your source code. It’s executable. You can run commands against it. An app, is merely a wrapper / directory, which includes that binary and other things. How do you create a binary? First it’s important to understand what a binary is. You’ve used them every day in the terminal. Examples: ls, cp, mkdir. You pass certain parameters to them. They don’t have any file extension....

Ranges in swift are super simple to create. Yet they come in various forms. let r1 = 1...3 let r2 = 1..<3 let r3 = ...3 let r4 = 3... let r5 = ..<3 They all have range like characteristics, but have slightly different traits. It’s because they’re actually different types. Different Range Types let r1 = 1...3 // ClosedRange<Int> let r2 = 1..<3 // Range<Int> let r3 = ...3 // PartialRangeThrough<Int> let r4 = 3....