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Koans as Ontological Formulas

Level of difficultyHard
Reading time8 min
Views133

Notes on the Forgotten Nature of Zen Koans

I don’t know how koans were perceived when they sounded like thunder. Perhaps not at all as they are analyzed by modern philosophers. Perhaps koans were not analyzed, but lived. And it is impossible to transmit a lived experience across centuries. It is an individual experience. Well then, perhaps we have lost the essence of koans. Or perhaps we never knew it. In that case, I can very well allow myself to present koans as I see them.

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The Billiard Fractals

Level of difficultyHard
Reading time25 min
Views888


Complex systems often appear chaotic or incomprehensible, yet closer examination reveals that such complexity can frequently be reduced to a simple underlying mechanism. By systematically removing layers of emergent behavior, one can uncover a fundamental rule or equation from which the entire system originates.

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DASTing SAML: Breaking Trust, One Assertion at a Time

Level of difficultyHard
Reading time14 min
Views1.3K

My name is Ilya and I’m a Core Developer at Bright Security. In Bright we work on a DAST (Dynamic Application Security Testing) solution that helps development teams find and fix vulnerabilities early, straight from CI/CD. My own path began in full-stack engineering, but almost a decade of shipping production code drew me ever deeper into application security. In this article I’m explaining key approaches on what SAML actually is and how we detect it in Bright using DAST.

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How to build and run calculator from Windows XP using GCC x64?

Level of difficultyHard
Reading time63 min
Views1.2K

Hi Everyone!

In this article we a little bit will analyze of code of Windows XP and will compile the calculator application using GCC x64 in Windows 10 environment. We will look what kind of errors I faced during the build and the methods how to solve them. At the end we will launch the build of the calc.exe application.

Have a nice reading!

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互联网屏蔽是如何工作的:使用实例概述现代方法

Level of difficultyHard
Reading time2 min
Views1.9K

一组印度科学家发表了以其本国为例政府机构采用的现代互联网屏蔽方法概述。他们研究了互联网服务提供商限制访问被禁信息的机制,评估了这些机制的准确性以及绕过这些屏蔽的能力。2captcha常驻代理团队整理了这项研究,并提请大家关注这项工作成果的主要论点。

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Spring Cloud Gateway: The Single Point of Entry or Failure – a Path to Non-Blocking API Gateway

Level of difficultyHard
Reading time20 min
Views3.7K

Hello Habr! My name is Nikita Letov. I am a tech lead of backend development in remote banking services for individuals (or retail department) of Rosbank. In this article I will describe what a point of entry to an app is, when it becomes vital, and how API Gateway can help you. We'll review a traditional blocking pattern based on Netflix Zuul 1.x gateway with all its problems of using, then reactive Spring Cloud Gateway and difficulties of moving to it. Finally, we'll compare these two approaches.

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New plasma rocket engine: A promising experiment harnessing a hybrid of chemical and ion technology

Level of difficultyHard
Reading time37 min
Views2.2K

 Gleb Kulev, Candidate of Technical Sciences

The rapid exploration of outer space has faced a problem related to the insufficient efficiency of modern rocket engines. As a solution to this problem, the concept of a jet engine based on new operating principles is proposed, using a combination of known physical laws and having advantages over known types of jet engines.The article presents the results of testing three modifications of jet engines based on new operating principles and their analysis. The article discusses the physical principles of operation of a jet engine based on new principles, its advantages and problems arising during its creation.

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Anonymous identification for groups

Level of difficultyHard
Reading time13 min
Views681

The identification protocol based on the pairing function, resistant to impersonation and compatible with the instant digital signature (IDS) mode, was studied in this article. This protocol uses prover's and verifier's public keys. As a result, there is no anonymity, since certificates including personal data of their owners are issued for the mentioned keys. This article contains a description and analysis of new anonymous identification protocols for groups.

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LeetCode, Hard++ (Acceptance 24%, Latest): 2867. Count Valid Paths in a Tree. DFS. O(n). Swift

Level of difficultyHard
Reading time2 min
Views1.8K

The intuition is to employ a depth-first search (DFS) approach through the tree.

During each step in the traversal, we perform the following key calculations:

1. Determine the path that ends at the current node.

2. Compute two different subtree paths that traverse the current node.

3. Maintain an array that keeps track of the cases where paths contain either 0 or 1 prime number.

This method allows us to efficiently count the valid paths in the tree while considering the presence of prime numbers.

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LeetCode, Hard: 2818. Apply Operations to Maximize Score. Swift

Level of difficultyHard
Reading time4 min
Views1.3K

Time complexityO(max(nums) * log(max(nums)) + n * log(n)). Accounting for computing prime scores, using the stack to compute next greater elements, and sorting the tuples.

Space complexityO(max(nums) + n). Considering the space required for arrays and the stack used for computation.

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LeetCode, Hard, last two problems: 2809. Min Time to Make Array Sum At Most x & 2813. Max Elegance of a K-Length Subseq

Level of difficultyHard
Reading time3 min
Views937

2809. Min Time to Make Array Sum: Efficient Swift solution, using dynamic programming, for minimizing time to reach a sum in arrays A and B. Time: O(n²), Space: O(n).

2813. Max Elegance of K-Length Subseq: Swift code for elegantly selecting unique k-length subsequences with profit and categories. Solution uses sorting and iteration. Time: O(nlogn), Space: O(n).

Github: https://github.com/sergeyleschev/leetcode-swift

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LeetCode 2532 (Hard++, Extra Category, Amazon). Time to Cross a Bridge. Swift solution

Level of difficultyHard
Reading time5 min
Views1.3K

Hard++, Extra Category.

Amazon.

Overflow checks have been taken into consideration. The maximum time to move a box is at most 4 * 1000 (four steps to move the box, each taking 1000 time). With at most 1e4 boxes, the total time is at most 4e7, ensuring the solution is safe.

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LeetCode 2612 (Hard). Minimum Reverse Operations. Swift. BFS. O(n+k). O(n)

Level of difficultyHard
Reading time3 min
Views1.7K

LeetCode 2612 (Hard). Minimum Reverse Operations.

The algorithm follows a breadth-first search (BFS) approach to determine the minimum number of reverse operations needed to bring the 1 to each position in the array.

To speed up the algorithm, we mark banned positions with -2 instead of using set lookups. This optimization reduces the constant coefficient and improves the speed of the algorithm, but it may still result in a time limit exceeded (TLE) error.

For each visited position, there are potentially O(k) target positions that can be reached through reverse operations. To avoid the multiplicative cost of iterating over all these potential positions, we update the nextNode2s array. This array initially points forward by 2, but we update it dynamically to point beyond all the target positions considered for each visited position. This optimization helps improve the efficiency of the algorithm and avoids unnecessary computations.

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LeetCode 956 (Hard). Solution of the day. Tallest Billboard. Swift. DP

Level of difficultyHard
Reading time2 min
Views2.4K

Solution of the day.
LeetCode 956 (Hard). Tallest Billboard.

The code uses dynamic programming to solve the problem. It maintains a dictionary dp, where the keys represent the possible height differences between the two billboards, and the values represent the maximum sum of heights achieved for each height difference.

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