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Algo Note: the idea of some sorting algorithms

I will give all examples in ascending order, just change the judgement clause when you need descending order. $O(n^2)$ sorting algorithms Selection Sort The idea is, always select the smallest v...

Posted by Daniel's Blog on October 20, 2025

DS Note: Monotonic Stack

Posted by Daniel's Blog on October 3, 2025

DS Note: Trie / Prefix Tree

LeetCode Problems 208. Implement Trie (Prefix Tree) 211. Design Add and Search Words Data Structure 212. Word Search II In previous problem, you should use DFS instead of BFS, or you will TLE. ...

Posted by Daniel's Blog on October 2, 2025

Some Python Phrase you should never write

Example 1 Never write: 1 [[0] * 5] * 10 this clause you can only use once, [0] * 5, like this. But if you use [[0] * 5] * 10 instead of [[0]*5 for _ in range(10)], that will make your variable ...

Posted by Daniel's Blog on October 1, 2025

How to Uniquely Decide a Tree From its Traversal

Very short conclusion: at least two traversal can uniquely a tree from the traversal, and one must be inorder traversal.

Posted by Daniel's Blog on October 1, 2025

Amazing proof methods on Permutations

The problems come from the book A First Course in Probability by Sheldon Ross. But I am really sorry since I forgot where the solution I saw, maybe another book, Wikipedia, or maybe some other onli...

Posted by Daniel's Blog on September 11, 2025

Why I think the iPhone 17 Offers the Best Value?

Personally, I believe the iPhone 17 is the most worthwhile option in the new series. Released on September 9, 2025, the iPhone 17 brings a significant balance between price and performance, much li...

Posted by Daniel's Blog on September 9, 2025

What I saw at Seattle

At Seattle. Before landing, a warehouse? of Boeing. You know, Boeing is located at Seattle. Airbus A350-941 (reg N505DN) of Delta Airlines (DL). A very cutting-edge model, strongly recommend by ...

Posted by Daniel's Blog on August 18, 2025

优雅且高效的权限管理——利用位运算

权限管理是开发中常见的场景，传统方法可能依赖数组、字典或数据库，尤其是在权限很多的情况下，大量的变量命名以及重复运用会增加代码的复杂度，而且更容易出错。今天分享如何用 位运算 来管理权限，包括 赋予、移除 和 检查 操作。 什么是位运算？ 位运算是直接对整数的二进制位进行操作的方式。Python 提供了多种位运算符，例如： &（按位与）：两个对应位都为 1 时结果为 1。 ...

Posted by Daniel's Blog on December 10, 2024

AI不是万能的 博客维修日志_20241207

Make blog great again!

因为我的博客是GitHub Pages搭建的，纯静态也主打迁移方便。当然今天写文章的时候报错了。 build The current runner (ubuntu-24.04-x64) was detected as self-hosted because the platform does not match a GitHub-hosted runner image (or tha...

Posted by Daniel's Blog on December 7, 2024

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