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How to access real-time smart contract data from Python code (using Lido contract as an example)

Level of difficulty Medium
Reading time 7 min
Views 111
Decentralized networks *Python *Solidity *Cryptocurrencies Data Engineering *
Tutorial

Let’s imagine you need access to the real-time data of some smart contracts on Ethereum (or Polygon, BSC, etc.) like Uniswap or even PEPE coin to analyze its data using the standard data scientist/analyst tools: Python, Pandas, Matplotlib, etc. In this tutorial, I’ll show you more sophisticated data access tools that are more like a surgical scalpel (The Graph subgraphs) than a well-known Swiss knife (RPC node access) or hammer (ready-to-use APIs). I hope my metaphors don’t scare you 😅.

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Modular grids in UX designer's work

Level of difficulty Easy
Reading time 8 min
Views 141
Web design *Interfaces *Mobile applications design *
Sandbox

Most novice web designers at the beginning of their journey still in the courses hear such a concept as modular grid, and wonder what it is and how to properly customize and use this tool.

From personal experience, I know that in many courses with titles "web designer from zero to pro" or " IU / UX designer in a month" this topic is either skipped, or give instructions, where they say everywhere to use a grid of 12 columns with margins of 80 to 100 pixels. And, as a result, it turns out that after taking these gore courses, a person sees beautiful works, thinks to repeat them, but the grid does not work, and the student, simply, does the work without a grid and completely forgets about it.

That's why I want to help beginners to understand this really voluminous issue.

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iOS Dev Skills. Performance Review

Reading time 2 min
Views 257
Development for iOS *Swift *Development Management *Personnel Management *
Digest

CTO: Balancing Leadership and Architecture.

As a CTO, effective leadership goes beyond technical architecture. Conducting regular performance reviews is a crucial part of managing teams.

Note: The performance review schedule may vary depending on the specific
company's policies and guidelines.

For early-stage startups, lacking CTO expertise in conducting performance reviews is common. In my experience, I've tailored grades to encompass all aspects of professional iOS development, keeping project-specific needs in mind. Being the first in the team can offer significant growth opportunities. However, acknowledging any lack of people management skills and compensating through continuous growth is essential.

I've compiled my insights on structuring the iOS development department, conducting performance reviews, and most importantly, emphasizing the significant distinctions between developers' levels based on well-defined criteria.

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LeetCode 2801 (Hard, Acceptance 14.5%). Count Stepping Numbers in Range. DP. Handles large inputs (10^9 + 7)

Level of difficulty Medium
Reading time 3 min
Views 265
Algorithms *Swift *
Case

Given two positive integers low and high represented as strings, find the count of stepping numbers in the inclusive range [low, high].

A stepping number is an integer such that all of its adjacent digits have an absolute difference of exactly 1.

Return an integer denoting the count of stepping numbers in the inclusive range [low, high].

Since the answer may be very large, return it modulo 10^9 + 7.

Hard, Acceptance Level 14.5%.
Dynamic Programming (DP).
Efficiently handles large inputs (10^9 + 7).

Latest and Most Hardest Problem.

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How to partition a MySQL table

Reading time 6 min
Views 361
MySQL *SQL *
Sandbox

Alright, folks! Get ready to dive into the world of MySQL table partitioning. In this guide, we'll cover why partitioning is so darn important for your MySQL tables. Plus, we'll dish out all the juicy benefits you can expect from partitioning a table. So, buckle up, and let's get started!

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Wie ich ein einfaches Monitoring von Kanälen mit Benachrichtigungen an Slack ohne Erfahrung gemacht habe

Level of difficulty Easy
Reading time 3 min
Views 204
Configuring Linux *.NET **nix *Network technologies *
Tutorial

Arbeiten im technischen Support brachte zusätzlich zu allen Aufgaben die Pflicht mit sich, die Kommunikationskanäle zu überwachen. Dies wurde über den Grafana-Dienst realisiert, der die erforderlichen Metriken aus Zabbix bezog. Da die Art der Arbeit jedoch bedeutete, dass man nicht immer an seinem Arbeitsplatz sitzt, kam mir die Idee, dies ein wenig zu automatisieren und Benachrichtigungen auf das Telefon oder zum Beispiel in einen Messenger zu erhalten, falls ein Kommunikationskanal ausfällt. Allerdings hatte ich keinen Zugriff auf das Zabbix-System und auch keinen erweiterten Zugriff auf Grafana.

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Total votes 5: ↑5 and ↓0 +5
Comments 0

6 Best Flutter Development Companies in the US 2023

Level of difficulty Easy
Reading time 7 min
Views 638
Development for iOS *Development of mobile applications *Development for Android *Flutter *
Review
Understanding the world of Flutter app development can be a challenging endeavor, especially for business executives seeking to create top-notch mobile applications. When it comes to choosing a Flutter development company in the US, finding a reliable and proficient partner is crucial for the success of your app. A wrong choice could result in wasted resources and a subpar app that fails to meet user expectations.

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Total votes 2: ↑0 and ↓2 -2
Comments 0

LeetCode 2790 (Hard). Maximum Number of Groups With Increasing Length. Solution of the day. O(N logN). Math

Level of difficulty Medium
Reading time 3 min
Views 867
Algorithms *Swift *
Case

Simple Swift Math Solution.

Time complexity: O(N logN).

The time complexity of this solution is dominated by the sorting step, making it O(N logN), where N is the length of the input array usageLimits. The rest of the operations involve simple arithmetic and comparisons, which take linear time. Therefore, the overall time complexity of the function is O(NlogN).

Only 10 lines of code.

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DAOs trends in 2023 — or why DAOs can become the leading one in web3

Level of difficulty Easy
Reading time 3 min
Views 294
Product Management *Cryptocurrencies
Analytics

Against the backdrop of a sharp decline in venture investments in various traditional industries (this is clearly related to the global economic situation), but against the backdrop of certain upheavals in the crypto industry, the question arises of a driver that can become one of the «pillars» of the development of a decentralized industry.

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Blockchain use in marketplaces — and how Account Abstraction can help it

Level of difficulty Easy
Reading time 3 min
Views 215
Product Management *Media management *Cryptocurrencies
Analytics

Today, it becomes quite obvious that the situation with web3 technology is becoming similar to the situation with programmatic advertising 10-12 years ago. When programmatic-ads just started, the major market players were not very optimistic - it was much easier for them to follow the well-known paths with chains of publishers and agencies. However, once programmatic got rid of the «childhood diseases» and became simple in use, effective in attracting customers, it has taken a dominant position in the modern advertising market - providing precise targeting and cost reduction. The situation with web3 is similar - all publishers ideally want to have systems for lifetime tracking of customer achievements (that is, Soul Bound tokens in web3), theoretically stable decentralized data storage systems that cannot be broken through a simple server attack, real users’ ownership for his content, as well as simple cross-border payment systems that have built-in algorithms for calculating all duties and taxes. Sounds like a perfect world, but even Amazon doesn't do that yet. Why?

The problem is the web3 entry point, which is difficult for users. As soon as they start talking about opening a crypto wallet, about 12 phrases as a backup, most users interrupt the onboarding process and immediately leave the site. This is obvious - over the decades of the development of the digital market, users have become accustomed to facilitating and simplifying systems for interacting with the site. One-click registration, effective convenient UI, visibility and the «metro principle», where the client is led by the hand – this is modern digital progress. And here some 12 phrases are offered, incomprehensible tokens - and, most importantly, why? So, it turns out that a self-sufficient audience of geeks or really advanced users revolves around web3, which is growing weakly.

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Stages of product work on the MVP of the AI course generator

Level of difficulty Easy
Reading time 2 min
Views 301
Website development *Product Management *
Sandbox

When developing functional digital products, especially at the preliminary stages (from MVP to alpha versions) many teams use the «technology first» principle. This means a minimum of user convenience, a maximum of engineering competence. When evaluating the potential of a product, further efforts are already in the direction of creating ergonomic visitor paths, design and more. However, here lies the catch - since not two clients or a prospective investor can evaluate the entire user route, touch it with their hands and make sure that the system works, you can lose both clients and partners.

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SEO Tips to Magento 2 Product Pages

Reading time 3 min
Views 209
Search engines *Product Management *Magento *
Sandbox

Avoid duplicate content

Many online merchants face a common challenge with multiple product variations, leading to duplicate content issues. When similar products have slightly different URLs like "?=sortby" or "?p=2", search engines may view them as duplicates, impacting your website's credibility and search rankings. To tackle this:

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Review of mini-book «60 terrible tips for a C++ developer»

Level of difficulty Easy
Reading time 6 min
Views 597
PVS-Studio corporate blog Programming *Perfect code *C++ *C *
Review

I wrote a small e-book about terrible tips for C++ developers. Actually, it describes bad programming practices and explains why it's better to avoid them. However, every chapter of this mini-book starts with a terrible tip — just for fun.


60 terrible tips for a C++ developer


By the way, these tips may seem artificial but believe me, they are based on the real experience. In other words, the described terrible tips occur in developers' lives — that's why it's worth discussing them. First of all, this book will be useful for junior developers. But more skilled C++ developers can also find interesting and useful tips.


Even though it's a mini-book, it clearly does not fit into the Habr format. Too many words. So, I decided to write here the review. Here is the link to find the full version of the mini-book: 60 terrible tips for a C++ developer.


If you still hesitate whether to read it or not, below you will find a list of terrible tips that will be discussed in the mini-book.


View the terrible tips:

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Total votes 10: ↑7 and ↓3 +4
Comments 0

On Schnorr identification protocol compatibility with instant digital signature mode

Reading time 6 min
Views 189
Information Security *

The article describes the interactive Schnorr identification protocol (hereinafter referred to as the Schnorr protocol) and formulates the problem of compatibility of this protocol with the instant digital signature (IDS) mode. This post shows how to modify the Schnorr protocol to provide such compatibility.

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APRS. AFSK modulator from Flipper Zero

Level of difficulty Medium
Reading time 7 min
Views 2.9K
C *Development of communication systems *
Tutorial

There is such an interesting data transfer protocol - APRS. A lot has already been told about him on the Internet. There will be no in-depth theoretical material here. This article will describe how to create your own "pocket" AFSK modulator. In the following articles there will be instructions for going on the air and for creating a simple demodulator. Which will allow you to accept APRS packages and display information on the display right on the street. Everything will be implemented for Flipper Zero. If you don't have this gadget yet, then don't worry and try everything on the great and terrible Arduino. It is very interesting to transmit information at a distance "with your own hands".

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Total votes 3: ↑3 and ↓0 +3
Comments 2

Spring Data JPA entity enum converter

Reading time 4 min
Views 742
Programming *Java *Perfect code *Designing and refactoring *Concurrent computing *
Case

Faced with situation when had to map STRING VALUE coming from database TO ENUM. The problem happens when value stored in database differs from enum name. And here we need a workaround to make a mapping. I will describe main points on how I was able to realise it.

Entity field converter?
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How to make a robot? What is first

Level of difficulty Easy
Reading time 3 min
Views 1.1K
JavaScript *Node.JS *Robotics development *Development for Raspberry Pi *Robotics

I develop robots, and I'm often asked, "How to make a robot?" and "Where do you find information and what resources do you use?"

If you don't know where to start and want to create your own robot, this article is for you. In it, I will try to explain the process and also share the first steps you should take.

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Total votes 2: ↑2 and ↓0 +2
Comments 0

Supercharge Your React Projects with Custom Hooks

Level of difficulty Medium
Reading time 42 min
Views 3.2K
Website development *JavaScript *ReactJS *TypeScript *Visual programming *
Tutorial

In this article, we dive into the world of custom React hooks and explore the incredible potential they hold for supercharging your work projects. With over 20 carefully crafted hooks at your disposal, I personally utilize these hooks in my own work projects, and now I'm excited to share them with you. From enhancing functionality to streamlining workflows, these custom hooks are designed to empower developers and deliver user-friendly experiences. Join us on this journey as we unleash the power of these 20+ hooks and unlock new levels of productivity and innovation in your React projects.

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Total votes 1: ↑1 and ↓0 +1
Comments 2