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· 13 min read
顾淇元 Alex

在今天 C 社 OI 部的活动中,我们先进行了破冰活动——自我介绍并交流有趣的算法知识。通过这独特的形式我们得以增进对彼此的了解,并为之后的合作打下基础。

之后,我们挑选了最感兴趣的网络流这一类算法问题进行详细的讲解。我们从网络流图的基本概念开始,例如源,汇点剩余容量最大流最小割 等等。其中最为趣味的是最小割,其定义为删去若干条边使得某两点 (u,v)(u,v) 不互通,这若干条边边权和的最小值。

接下来通过不断优化算法,例如灵活运用 Edmond-Karp 动能算法(复杂度 O(nm2)O(nm^2) ), Dinic 算法(复杂度 O(n2m)O(n^2m) )和 ISAP 算法(复杂度 O(n2m)O(n^2m) ,不需 BFS 多次)。此外还讲解了一个优美的定理:最大流最小割定理。这一定理在一些图论问题中有着有趣的应用:

· 5 min read
Josh Cena

This is the fifth activity of Computerization algorithm team. Because the December USACO contest is almost there, we had some targeted practicing, starting with Bronze problems. Because members already have decent understanding, we chose a tough one. Bronze division problems only require mastery of loops, so a brute-force enumaration will always work, with no requirement of algorithms or data structures.

· 4 min read

This is the first activity of Computerization algorithm team. We discussed a problem from Shanghai NOI regional selection, which leverages state compression dynamic programming. The mathematics is beyond our capacity to be rigorously proven.

· 3 min read
Josh Cena

This is the first activity of Computerization algorithm team. We introduced the method to find the nnth term of the Fibonacci sequence, which mainly uses matrix exponentiation.

· 8 min read
Josh Cena

This article is migrated from the first section of the file in the new member practice commit repo.

You can either add a file via Graphical-User-Interface(GUI)-powered GitHub Desktop or command line. You may begin with GUI, but you will someday get into command lines since they offer better control over your repo. Furthermore, Visual Studio Code users can try out the built-in source control.

We find it necessary to tell you what you are actually doing each step instead of having you follow the written instructions mechanically. This especially helps since things hardly go as beautifully as the tutorial expects. This section assumes no prior knowledge of any git operations.

· One min read
Josh Cena

Computerization welcome all new members of class 2020!

At Computerization, you can:

  • Join in the development of the new platform Enspire;
  • Research on artificial intelligence (e.g. neural networks, machine learning);
  • Take part in algorithm contests (e.g. LeetCode weekly contest);
  • Learn front-end / back-end technology and web designing, experience web development in the real world;
  • ...

We hope that all new members can learn with joy, self-improve, and meet peers with the same interest.