I have seen the knapsack problem show up in quite a few technical interviews. It is one of those problems that feels tricky at first but becomes much clearer once you see the recursive pattern underneath. In this tutorial, I will walk through the 0-1 knapsack problem, show you how to think about it recursively, and get a working Python implementation that you can actually use. The core idea is this: you have a set of items, each with a weight and a value. You have a knapsack that can hold only so much weight. Your goal is to pick…
Author: drweb
Use with open(file, “r”) as f to guarantee files close properly Iterate directly over the file object with for line in f for memory-efficient line-by-line reading Use path.read_text() from pathlib for a concise single-call read Pass encoding explicitly to open() to avoid encoding mismatches Build lists of dictionaries for structured text files you need to query How to Read and Parse a Text File in Python The standard way to read a file in Python is with the built-in open() function. You pass in the file path and a mode, where “r” means read. Then you call read() on the…
You can’t make this crap up. You just wish you could. Jer Crane, founder of the small vertical software company, PocketOS, reported on X that the AI Cursor coding agent and a Railway backup misconfiguration combined to briefly wipe out the company’s car‑rental customer production data. Not some of the data. All of it. That’s a company killer. Fortunately for PocketOS and its customers, Crane later reported that Railway had managed to “recover the data (thank God!).” Thanks to that miracle save of reconstructing the missing data from earlier backups, PocketOS and its customers are back in business. But how…
I keep coming back to Python classes because they are the foundation of every non-trivial program I write. After years of using them daily, I have a good sense of what actually helps someone grasp this material quickly and what just confuses people. This guide is the article I wish I had when I started. Python classes are not complicated once you understand a few core ideas. You define a class to create a blueprint, then you instantiate it to get objects that hold data and can perform actions. That is the whole idea. Everything else in object-oriented programming is…
OpenAI has unveiled Symphony, an open-source specification that shifts how software development teams deploy AI in workflows, moving from interactive coding assistance toward continuous orchestration of autonomous agents. Symphony reframes project management tools as operational hubs for AI-driven coding. Rather than prompting an assistant for individual tasks, developers assign work through issue trackers, allowing agents to execute tasks in parallel and deliver outputs for human review. The change reflects a trend in enterprise AI in which systems are increasingly embedded into production pipelines rather than used as standalone tools. Symphony emerged from internal experimentation at OpenAI, where engineers attempted to scale…
WireGuard is a modern VPN protocol built directly into the Linux kernel since version 5.6, and this guide walks through the full server and client setup on Debian 13 (Trixie) using nothing but the standard package manager and a handful of config files. Most sysadmins still reach for OpenVPN out of habit, but these days that often means accepting a slower tunnel, managing a certificate authority, and dealing with a config file that can run to 50 lines before you’ve done anything meaningful. WireGuard does the same job with just two config files, a key pair on each side, and…
I remember the first time I tried to build a predictive model in Python – I had data, I had a vague idea of what I wanted, but I had no clue how to connect those two things into something that actually worked. That confusion is normal. Predictive modeling sounds intimidating because it sits at the intersection of statistics, machine learning, and software engineering. Let me walk you through exactly how it works, with a complete example you can run yourself. Here is what I cover in this article: what predictive analysis actually is, why it matters, the step-by-step process…
I have been building delivery route optimization tools in Python for several years now, and I keep running into the same problem when teaching newcomers: most tutorials either oversimplify the problem or jump straight into external solvers like Google OR-Tools without explaining the underlying algorithms. My goal with this article is to walk through the core techniques that power real route optimization, step by step, using only standard Python libraries. In my experience, understanding these foundational algorithms gives you a massive advantage. Whether you need to solve a simple Traveling Salesman Problem (TSP) or a full Capacitated Vehicle Routing Problem…
You’ve been retyping the same long commands for years, but sudo !!, !$, ^old^new, and a handful of Bash history tricks can cut that habit down to almost nothing and this guide covers every one of them with real examples. You type a long apt command to install a package, hit Enter, and the terminal shows back Permission denied. So you arrow-up, jump to the beginning of the line, type sudo, and hit Enter again. That little dance takes maybe 5 seconds, but you do it a dozen times a day, and it adds up, and that’s just one pattern.…
I keep coming back to base64 whenever I’m working with APIs, JWT tokens, or any system that needs to safely transmit binary data as text. The other day I needed to decode a webhook payload that came in as a base64 string, and I thought – I should write down exactly how I did this, because the gotchas are real. Base64 is one of those tools that looks simple on the surface but trips up a lot of people. You take some bytes, you get a string. You take the string back, you get bytes. Easy – except the encode/decode…