These days I find my disks almost full, and want to find some tools to scan my disks and find out the large files that occupy the space. After some simple searches, some free software are found. However, it seems that they are not open source, although some of them are free (of prices). So I make some deeper searches. Finally, I find out two analyzers are provided by the open source community:…
How to package and encrypt files or folders easily using symmetry password in unix way? tar -> gzip -> gpg to rescue. Here is my quick note. Every reader should use the command at the own risk. No guarantee is given that the generated files are uncrackable or crackable using the command below. Suggestion: always choose a strong password. The code is released under GPL. See these for references:…
This is the quick note before and after installing Windows 10 pro. installing Windows: download: https://www.microsoft.com/software-download/Windows10 remember to add this file \sources\ei.cfg so that we can select installing home or pro during installation: [Channel] Retail Windows features search “Turn Windows features on of off” enable Hyper-V and Windows Subsystem For Linux Chrome: offline…
有段时间频繁搬家，觉得购买电子书很方便，不用带着走，也可以说随时带着走。所谓的时代便利也。 然而内心总对电子书有些不安。这倒不是“纸质书味道更醇厚”之类的虚无缥缈的原教主义理由，而是切切实实的。 国内外的几大付费电子书平台（kindle、多看、豆瓣等），都不允许下载到本地，只能在线观看。万一哪天供应商删库跑路了，被黑客入侵了，修改用户协议了，等等，内容就会消失殆尽。本质来说，这类电子书只是“租借”了一种“平台没跑路前的永久阅读权”。 而实体书，沉甸甸的一叠纸，只要保养得当甚至几百年都可能能保存下来，它的存在与否大体是取决于主人自身对命运的把控——当然这也只是一个美好祝愿——而不是外部平台的决定。 终究时代不同了，几代人之后可能对“书本”的定义都是和屏幕、租借——尤其是订阅制横行——等概念绑定的，不知道他们能不能理解“古人”因实体书的沉重而带来的嫌弃和安全感呢。
A few days ago, I wanted to transfer photos from my iPhone to my computer. But it was very annoying that after copying for a while, the process stopped with some errors occured. After some searching, I found the reason: iPhone automatically transfer photos to JPEG format but the process was not stable. Here is the fix: Settings App -> Photos -> TRANSFER TO MAC OR PC -> choose "Keep Originals"…
In Windows 10 Anniversary Update and later Creators Update, if we press “shift” key and right click on desktop, drive, folder, folder blackground, we could see the menu “Open PowerShell window here”. It’s convenient for development. But how to reveal the menu? After searching on the Internet for a while, I found the clear solution on TenForums and decided to note it down here. In short: “Win + R”,…
字体发布 继 2014 年 Adobe 发布 思源黑体 之后，现在 2017 年 Adobe 发布了 思源宋体 ！两者都开源！不要钱！走过路过不要错过！这是一种什么精神？！一种国际主义精神！ Noto Sans CJK 和 Noto Serif CJK 又是什么鬼？ Noto 是 Google 贴牌的字体族，其中的中日韩字体部分，由 Google 和 Adobe 等共同开发。所以，两种字体的中日韩部分是一样的，一字两表。 那么问题来了，使用哪个？ 我也受到这个问题困扰很久。没有特殊情况下，应该是 安装其中一种就够了 。 推荐 如果没有意外，以后的 Android 的 CJK 字体必然自带 Noto CJK 的！而且，现在的 Ubuntu 已经全面拥抱 Noto Sans CJK 了。所以出于实用主义缘故，使用 Noto Sans CJK 和 Noto Serif CJK…
tl;dr This post shows how to use Electron as the GUI component of Python applications. (Updated version of one of my previous posts.) The frontend and backend communicate with each other using zerorpc . The complete code is on GitHub repo . important notice This post and README.md on GitHub repo should be the same. If there are inconsistencies, the README.md on the GitHub repo is more accurate.…
topological sorting can be solved using DFS and BFS in asymptotical time complexity $O(V + E)$. The problem LeetCode #210 Course Schedule II is an excellent exercise for us to practice the solution to topological sorting. The problem is int[] findOrder(int numCourses, int[][] prerequisites) . For (the official) example, one answer to 4, [[1,0],[2,0],[3,1],[3,2]] is [0, 1, 2, 3] . We should pay…
tl;dr Remember the core idea in React : UI = func(const props, state) . what exactly is React? Quoted from the official page : “A JavaScript library for building user interfaces”. Nothing more and nothing less. And I would like to conclude the code idea of it: UI = func(const props, state) , nothing more and nothing less. While you are searching tutorials about React online, many fancy words bump…
tl;dr I choose to use create-react-app , then use ES2016 standard to write react to build the UI and use redux to manage the data, and write flexbox to manage layouts in CSS, if I am going to start a completely new general-purposes front end project in early 2017. disclaimer This post only expresses my current opinion and suggestions and I am not responsible for any potential lost or profit for…
tl;dr This post discusses the $O(n^2)$, $O(n log(n))$ complexity methods to find the length of longest increasing subsequence (LIS), and the way to recover the subsequence. the naive dynamic programming … which has $O(n^2)$ time complexity. dp[i] is the max length of LIS ending with nums[i] . Thus we have dp[i] = max(dp[j], 1) for 0 <= j < i and nums[j] < nums[i] . import java.util.* ; public…
小周醒了过来。 “呃讨厌，不得不起夜了，都怪睡前喝水太多。”他无奈地想。半夜要起床是仅次于白天要起床的第二不爽事情。他艰难地睁开眼睛，却发现左眼似乎被眼屎糊住了只能睁开一半，右眼能睁开大半却觉得眼花。 小周决定就这样半睁着眼去洗手间。毕竟是自己天天生活的宿舍，按道理半闭着眼睛都能走到过去。他干脆闭着眼睛走到房间门口，随手打开房间灯——“咦，怎么还是这么暗，没理由啊。”他再次摸索在墙上的那个房间电灯开关。“明明扳了到开的状态的？”他再次扳动了开关，尽管还是半闭着眼的状态，他按道理能够感受到光照的，却没有这个感觉。小周再次摸了摸墙边的开关，冷汗流了出来——手上的触感告诉他开关还处于关的那个状态位置。…
introduction Edit Distance is a famous algorithm problem solved by dynamic programming. I heard it for multiple times, until now I understand the solution after having an algorithm class. problem Given two strings word1 and word2 , everytime we are allowed to insert , delete , replace a character of word1 . Return the minimum number of steps to convert word1 to word2 . solutions DFS It’s not the…
Hadley’s ggplot2 book is a useful resource about learning his ggplot2 package. He generously provides the online version for us to read. But how to compile and get the (personal) pdf version from the repo? I figure it out and note down here. I am working on Windows 10. To sum up: we need these working in command line: git R xelatex make optipng pandoc . Then make clean && make . pre-installation…
Heapsort is one of the algorithms for sorting, with average time complexity $O(n log(n))$ and worst $O(n log(n))$, and space complexity $O(1)$. I think it’s kind of interesting, so I write down the Java implementation here. Previously I was familar with the top-down ( siftUp() ) method, but in this post I write down the buttom-up ( siftDown() ) way, based on Wikipedia. Firstly heapify() using…
Quicksort is a usual algorithm for sorting, with average time complexity $O(n log(n))$ and worst $O(n^2)$, and (stack depth) space complexity $O(log(n))$. As an exercise, I wrote down the quicksort for array and linked list in Java here. For the array, the code is kind of trivial. Select the first element as the pivot, then scan and swap the elements less than pivot with the elements at the…
what While developing on Windows, sometimes I need to switch to a *nix-like environment. Right now Docker has released the Docker for Windows . But the documents are lacking and I did not use Docker too much before, so sometimes I got confused, and here are some notes. docker installation We can download the stable or edge version. Moreover, we need a Windows 10 pro + with the Hyper-V virtual…
As of now ( April 2016 Aug 2019), there are two free domain email services available: Yandex.Mail for Domain (originally in Russian and you need to switch language if you read English) and Zoho Mail Suite , while Microsoft and Google have cancelled their free domain email plans. Yandex is a Russian website and it provides generous quota for free. So I decide to give Yandex a try and note down some…
what I just bought Thinkpad X1 Carbon 4th gen (2016) (20FB) . So far so good. I am feeling great satisfaction. Some notes Disable secure boot and enable virtualization. If want to cleanly install Windows 10, go to official TechBench to download latest Windows 10 iso file. We should use diskpart to format the disk if necessary: select disk 0 clean convert gpt create partition efi size=400 format…
2015 年 12 月 20 日上午 10 点到 11 点，对我的人生来说很重要，谢谢你。 果然所有事情都是连在一起的呀，我们称之为命运。
what In the lecture Corporate Finance , Teaching Assistant Jessie Wang provides an excellent note. notes Cash Flow Present Value: $V_A = \sum_{t=1}^{\infty}\frac{C_t}{(1+r)^t}$ Net Present Value: $NPV = PV - Investment$ Annuity: $\frac{B}{r-g} ( 1- (\frac{1+g}{1+r})^t)$ Perpetuity: $\frac{B}{r-g}$ rate of sub-period CF: $r_{sub} = (1+r)^\frac{1}{N} - 1$ delayed CF: $\frac{V_{future}}{(1+r)^T}$…
what Let’s Encrypt is an awesome project providing free SSL certs to the world. In Dec 3, 2015, it entered public beta. It says : Anyone who owns a domain name can use Let’s Encrypt to obtain a trusted certificate at zero cost. why For the glory of Santa of course! Well… Because security is important, so we should take enabling https into consideration. why this post However, the client doesn’t…
偶尔会发一些奇怪的梦。比如说这两。 1 昨晚发了一个奇怪的梦。 半夜热得醒来了，看了看手机，发现在不同国家留学的小钟同学也失眠了发了个微信朋友圈。于是起来和小钟聊了聊微信：“你咋也失眠了”“压力大啊。你在干嘛呢？”“哦我起来坐在沙发上玩电脑了，热得睡不着。”小钟回复到：“这么巧，我也是啊！我们拍个自拍合照吧！你摆好姿势呗。”我想了想，好啊，反正无聊，于是摆了一个俗套的 V 字型手势。 过了几秒，小钟微信上说“好啦！我们的姿势还行。”于是发来了一张我们并排坐在沙发上微笑的照片，都是左手在玩着电脑，右手在摆着 V 字的俗套姿势。 2 其实昨天发了第二个梦。这个梦更加好玩。长文。 半夜醒来玩了玩电脑聊了聊天，之后困了回去继续睡觉。无奈早上七点钟的时候被一个电话吵醒了。“你好，我是苹果公司的客服。经过我们的检测，你一天问 Siri 十次 what is the weather like today…
important notice Do NOT need to read this post. Please checkout the updated post for a better solution and a better explanation. what Electron (formerly Atom Shell) is a desktop node.js-powered “shell”. It is designed by Github and used to build Atom Editor . Python is a simple and powerful programming language. This post is a note about how to use Electron as the desktop GUI for Python…
Here are some notes for LaTeX. All from a guy’s blog: 始终 . LaTeX 的中文 曾经 LaTeX 的中文处理非常繁琐，现在日新月异，LaTeX 的中文处理在一般情况下已经很便捷，再也不需要折腾。 要求：安装最新的 TeX Live 2015 / MacTeX 2015 （重点是需要其中的 CTeX 2.0 宏包）。使用 XeLaTeX。 如果需要中文版式： %!TEX program = xelatex \documentclass [UTF8] { ctexart } \begin{document} 这个文档有中文版式和自动的字体配置。 \end{document} 如果只是插入一部分中文，不需要中文版式： %!TEX program = xelatex \documentclass { article }…
Mathematica is a great solution to some computing problems. However it has only one disadvantage: it is very expensive. Any other way to avoid the fee? No, I am not talking about swithching to R, Python, etc. Firstly, consult the university if being a university student. I found that many universities in United States provide Mathematica to their staffs and students, allowing them install it on…
I began learning English at age of 10 in primary school. However, it is in 2005 that I fell in love with English and realized its importance in my life. In 2005, the sixth book of Harry Potter was released. As a big fan of the Harry Potter Series, I could not wait to read the new book. However, the Chinese edition did not come out at that time. Coincidently, my relatives came back from UK with a…
Dual Thrust is a very simple but seemly effective strategy in quantitative investment. Attention: I am NOT responsible for ANY of your loss! strategy After the close of first day, let m = max(FirstDayHighestPrice-FirstDayClosePrice, FirstDayClosePrice-FirstDayLowestPrice) , then let SecondDayTrigger1 = m * k1 , SecondDayTrigger2 = m * k2 . SencondDayTrigger1 and SecondDayTrigger2 are called…
前言 最近想试一下捣腾一个 R 包出来，故参考了一些教程。现在看到的最好的就是谢益辉大大之前写过的 开发R程序包之忍者篇 ，以及 Hadley 大神（ggplot2 devtools 等一系列包的作者）的 教程 。但是前者有一些过时，后者是全英文的，所以我这里记录一下比较简单的过程，给读者们一个参考思路。如果你有一些 R 程序，想塞到去一个自创的 R 包中，那么这篇文章就可能是你想要的。为了方便说明，这里用我的包来进行示例。 准备工作 安装好 R。 可能需要 RStudio，没有的话也没有影响。 如果你是 Windows 下，请安装 rtools，去官网下载 exe 安装；如果你是 Linux 下，请安装对应的 R 开发包，Debian/Ubuntu 下就是运行命令 sudo apt-get install r-base-dev ；如果你是 OS X 下，要装好…
experience My Hackintosh crashed a few days before. What’s worse, I couldn’t install OS X 10.9 Maverick any more because some wired stuff! :-( So in case I want to do something relative with *nix, I wanna install a desktop Linux now. And for safe, I am installing it in a virtual machine firstly. Long days before, I was accoustomed to use Ubuntu. In fact I started to use it from 08.10. And…
Skype 是一个经典的网络电话服务。 这几天，因为一些事情，需要想办法从中国大陆打电话到美国那边。当时我被中国移动 0.80元/6秒 的昂贵花费吓到了，于是义无反顾地选择了 Skype 的方法。由于这方面的中文资料不是很多，因此这里分享一下具体的操作方法。 Skype 中国大陆的业务是由 Tom 来接管的。因此在中国大陆访问 http://www.skype.com/en/ 多半会被转接到 http://skype.tom.com/ 。据说大陆版的客户端有一些奇怪的问题，所以强烈建议大家都下载国际版来用。这里提供 20131010 的国际版的客户端的地址，链接另存为即可。 Windows 客户端 http://download.skype.com/SkypeSetupFull.exe Linux 客户端通用版…
找回高中的笔记本，然后把其中不错的诗词整理出来了。有诗词有对联。 无题 by S 流霞漫醉，应残叶飘零，朔风未息；……低吟微啜，独念来年归客。 青玉案*念有负旧人 by e10t 相逢欲语恨塞言，又一年，愧相见。三月长风驱黄叶，枝头新绿，不似春天。短柳苦难牵，金鞍貂裘傲气扬，怎料今，落魄相。多情忍作无情样，非懒回顾，只恐倩影，一望断一肠。 青玉案*念有负旧人 by Man 去时无风雨帘，离愁泪，反成霜，无色犹寒故情念，青竹如眠，春来非晚，只是红尘淡。抚剑柳下轻招扇，逝年华，唏嘘脸。久逢斜桥两相谦，人容似倦，过亦无言，何处伤痕乱。 青玉案*念有负旧人 by fy 犹记去年枝相缠，今何年，叶繁天。树似人同事变迁，共笑不再，愧语失言，柳短欲牵断。金鞍貂裘傲风扬，现夕阳，落魄相。水虽多情无情倘，忍不回顾，一望倩影，一曲悲肠唱。 卜算子 by fy…
At last, I installed Mac OS X Mountain Lion 10.8.3 in my Thinkpad T410, though I thought never using hackintosh before. I am getting used to OS X and considering transferring all my working flow into OS X now. In my old passage, I prefer avoiding hackintosh because of the sucking hardware driver support, and the difficulty to build up the prefect system environment. But the world is developing…
也算是开始放寒假了，开始有一段比较“长”的时间住在家里。 可是有一些不对劲。 我在家里自己的房间睡醒了，总觉得不对劲。床褥，衣柜，桌面上的公仔依然一样，静默地等待着我的回来，或者根本不在乎我有没有回来，依然沉默地呆在它们呆的地方。我又想到，此刻我放在宿舍的枕头书本，台灯等等，一定也是这样子，在灰尘的积累之中等我回去再见它们。两边的方寸之地带给我的感觉都是一样的。 可是它们不应该一样。我恍然，是房屋里的物事给了我一个陌生感。但这是我的家呀！哪里都可以陌生，这里却应该是最熟悉，闭着眼睛也可以在各房间之间穿梭的地方！ 我下午走出家门，在我这个自小长大的小城镇中游弋。在我长大的这些年头，城镇也在成长。哪里的吆喝声不见了，哪里的商铺改头换面，哪里的地方装修了。无论如何，城镇都变化了。老树开了新芽，朋友搬了新家，中学换了名字，牛杂不断升价………
忽然间想起来，某人有某个博客，似乎已经好久好久没有更新了。今天登上去，发现，最后一篇已经滞留在几年之前。 恍回多年前。 高中是一片湖，几只鸭子，一片小林，一条臭水渠，几座楼，几个人，晃来晃去的丑校服。三年了。湖还是那片湖，鸭子却死了，林还是那片林，似乎装修而砍了几棵树，水渠上还是有着小桥，水变清了，倒有了几分小桥流水人家之感，老师又成为了高三的老师，同学却早已不是那些人，标记着身份的校服都重新设计了。 物非人非，记忆终将无法考证，空寥寂寞。 那个时候，我们写下狗屁不通的句子，只求押韵不求平仄，偶尔有一两个意象，霎那构筑起悠远寂渺的意境，落地生根成优美的诗词；作为怕鬼的唯物青年，现实的理想主义者，爱文学的理科生，我们时常对遥远无垠的外面带着瑰丽的想象，对漫漫迷雾的未来长路有着璀璨的憧憬。 现在才发现，最美的诗与最美的梦一样，都是可遇不可求的。
These days, I wanna have a look at the hot and smart technology: Node.js. So I’d like to make some notes and share some useful resources. Node.js What’s Node.js? Javascript on the server side. What’s npm? The package manager for Node.js. npm for Node.js is as apt-get for Ubuntu. How to install it? I’m not talking about how to do it in Windows, because it’s bringing ourselves into troubles. Use one…
R is an useful software for statistical computing. And it has a package system, which enables users to install many interesting and useful packages. Here I note and recommend some. install.packages ( "ggplot2" ) # powerful printing system install.packages ( "devtools" ) # make dev life easier install.packages ( "knitr" ) # elegant report generator install.packages ( "reshape2" ) # use melt() and…
It’s quite important to acquire, deal with and import data for statisticso work. Here is some notes about acquiring and importing data in R. This post may be updated frequently. # first of all, we should know where we are: normalizePath ( "~" ) # change the working directory if necessary: setwd ( "~/tmp" ) # show the file in the directory: dir () # edit some file if necessary: file.edit ( "a.txt"…
关于三质点同时碰撞问题的一组特解 摘要 在低速运动力学下，两已知质量与初速度的质点完全弹性碰撞后的动能，动量情况已经被完整的研究并且得到解释解。但是，三个已知质量与初速度的质点同时碰撞后的动能动量情况依然没被研究清楚。本论文提出一种解决思路并且给出一组简单情况下的特解。 背景 两已知质量与初速度的质点完全弹性碰撞的情况下，若已知以下数据：质量分别为 m1，m2，初速度 v1，v2，设碰撞后两质点速度 x，y，则根据动量守恒定律与能量守恒定律可列得方程组： m1 * v1 + m2 *v2 = m1 * x + m2 * y 1/2 * m1 * v1 * v1 + 1/2 * m2 * v2 * v2 = 1/2 * m1 * x * x + 1/2 * m2 * y * y 动量守恒式为矢量式。 这里只考虑在同一直线上运动的两个质点，则有 v1 > v2，使用 Mathematica 得…
Never use Hackintosh. After many frustracted experiences, I had to believe the fact. A few days ago, I saw a man use a IdeaPad, and his screen attracted me: it runs max os (10.7.3 Lion). Actually, I heard of the “mystery” Hackintosh before. But it was the first time I saw anyone successfully insall it on a PC. “I love anything from Apple Inc. And the mac os is my major operating system instead of…
Nowadays, Jekyll (suddenly) becomes populars among hackers. In short, “Jekyll is a blog-aware, static site generator in Ruby”. It can be used to build a “static” blog, instead of using WordPress. Born in “static”, Jekyll does not have the problems such as security issues, C10K problems, php and database engines backend needed, software updates…… Considering that the comments, analytics can be done…
If Adobe open source Flash, it will regain the control of the web. It’s no doubted that Flash has greatly contributed to the development of the web. (Well, if it didn’t appear, will HTML standard be developed even faster? Who knows.) But today, Powerful JavaScript, improved HTML 5 and CSS 3 are going to replace it. New tags in HTML 5 such as video and audio can function like Flash. Angry birds and…
It’s likely that a new tipping point of the new style of education – including teaching and studying – is coming. Education , encompasses teaching and learning specific skills, and something less tangible but more profound: the imparting of knowledge, good judgment, and wisdom. It’s important to focus on and improve the way of interact between teaching and studying. It’s obvious that how students…
The year of Drangon in China is here. I define the topic of my life “high quality” in the new Chinese year now. Being addicted to web is harmful. Today, my blog’s domain has changed to www.fyears.org . wtfy.org will be kept for a while but not long. The rss addresses are http://feeds.feedburner.com/Fleeting-Years (not changed) or www.fyears.org/feed/ . (changed from …wtfy.org…). Feel free the…
Due to the exams at the beginning of 2012, I haven’t finished this post until now. It’s hard to image that the “fleeting” 2011 has passed with such a fast step. In fact, I began to rethink what I had done since I came to university, I always found that I had wasted so much time and fortunately catch some opportunities as well in 2011. 60 percent of the time in 2011 is my life as a freshman in…
某门课程要求写一下《共产党宣言》的读后感。于是在这里也发表一下。里面的想法有可能都是错的，但至少证明了我有读过，有想过。 《共产党宣言》真不愧为最伟大的政治宣言之一。我读完短短两万中文字的《宣言》之时的第一感觉只剩下震撼。 通篇是气势磅礴的句子，洋洋洒洒，从古到今。从资本主义的诞生以及其优越性谈到其已经不能适应其引领的生产力与生产关系的发展；从资产阶级对共产主义的质疑到反驳到阐述自己那“消灭阶级关系”的终极目标；从各种社会主义到共产主义的文献的曲折发展谈到被误用的表现和纠正；从当前各种政党的目标到团结一切力量来实现共产主义的号召。最后，“全世界无产者联合起来！”为整篇宣言的目的作出了最直接的表达。 然而，掩卷过后思索，震撼的余韵过去之后，有些想法浮现了出来。鉴于我对经济学的推崇和学习，第二遍阅读的时候我对其内容中的与经济学相关部分抱有的疑问很多。…
“Less is more.” It’s one of my favorite motto. While designing a project, a production, or an art, which I would like to say, I always prefer to make subtraction, until nothing should be thrown away or given up. However, while bringing the project out of the paper or the brain, I discover that it is much harder to remain the simplicity – the details, the additional must-have, and something…
#这个系列是为了写一下生活中的各种数字化洪流，名字取于 学而时嘻之 的同名文章 数字如潮人如水 -1- 从一次书展说起 昨天，我去了一趟书展。本来以为会是一场有意义的活动。结果去到的时候，我被吓倒了：诺大的会场里面人山人海，各个出版社摆成各种摊位，里面摆着不同种类的书籍，到处都贴着全场七五折的标语。在人群中忍着推推攘攘的我感到一阵茫然，而且我穿着凉鞋因而被人踩了不下N+1次，身高的差距使我不得不忍受奇奇怪怪的味道和沉降下来的二氧化碳…… 重点是，我找不到我想找的书。 没错，那里是有很多很多的书籍，五彩斑斓的封面充斥眼前。问题是，我不知道如何搜索，我拿起过几本书翻了两番然后放下，走到别的书堆前，然后我就失去了耐心，不停地逛啊逛，仅仅凭着书的封面和名字来感受一下它能不能“catch my…
Today it occurs to me that I haven’t seen you for such a long time. How are you? What are you doing? What are you interested in now? How about your new friends and are they as reliable as your old friends? What’s your hairstyle? What are you happy for or what is grieving you?…… All questions flood to me. But I don’t know. And I don’t know how to get to know. You seldom update your QQ, RenRen,…