Confessions from a Big Tech Hiring Manager: Tips for Software Engineering Interviews

March 28, 2021

Here is the link. 

Insights & advice from a hiring manager at Uber & Skyscanner. Books to prepare for the interview at Big Tech (Google, Facebook, Amazon, Uber, Stripe, Doordash & similar ones): - Cracking the Coding Interview https://geni.us/cracking-the-coding​ - Grokking Algorithms https://geni.us/grokking-algo​ - Systems Design Interview: an Insider's Guide: https://geni.us/systems-design​. Also, see my longer review: https://blog.pragmaticengineer.com/sy...​ - My more detailed writeup on preparing for the coding and systems design interview: https://blog.pragmaticengineer.com/pr...​ The book links above affiliate links: I make a small commission from purchases at no extra cost to you. More details: https://blog.pragmaticengineer.com/ab...​ 00:00​ - Intro 00:25​ - 1. Recruiter experience is not (always) indicative of the working experience 02:31​ - 2. The recruiter is on your side 04:55​ - 3. Preparation advice for Big Tech interviews 08:00​ - 4. Mindset before, during and after the interview 11:53​ - 5. Be fully present 16:23​ - 6. Interviews are a two-way street 17:31​ - 7. The interview experience can represent what a tough day at work is like 18:48​ - 8. It's not time wasted: it's experience gained Connect with me on other platforms: - Twitter: https://twitter.com/GergelyOrosz​ - LinkedIn: https://www.linkedin.com/in/gergelyor...​ - Newsletter on software engineering: https://blog.pragmaticengineer.com/ne...​ Books I've written (and am writing): - Software engineering resumes: https://thetechresume.com/​ - Building Mobile Apps at Scale: http://mobileatscale.com/​ - The Software Engineer's Guidebook: https://www.engguidebook.com/​ - All books: https://blog.pragmaticengineer.com/bo...

Weight control | 204 lb | Walk around neighborhood | two hours walk | 55 year old

 March 28, 2021

Introduction

It is hard for me to change my life style. I just decided to go out to walk around and spend time outdoor two hours. It is easy to do, since I chose to take some pictures and then make experience good memory. Enjoy sunshine, beauty of nature, and also hail. 

Photos taken

I asked my haircut lady how many gray hair I have, she told me that it is almost 50%. I need to compete with my gray hair, before it turns into 70 to 80%, I need to make sure that I stay fit, have good time to work and build wealth. 

I need to think about investing on long term on stock market, and build some wealth on stock market in next 6 to 12 months. Stay confident. Work hard on learning and practice some ideas, stay positive on value investing. 

How The Global Computer Chip Shortage Happened

March 28, 2021

Here is the link. 

It’s not an overstatement to say that semiconductors power the modern world. They’re not only a key component of nearly every electronic device we buy and use — they also power the factories that make the electronic devices we buy and use. And now, there aren’t enough of them getting made. Here’s how the global semiconductor chip shortage got so bad, and what’s being done to fix it. A chip shortage that started as consumers stocked up on personal computers and other electronics during the Covid-19 pandemic now threatens to snarl car production around the world. GM said that it would extend production cuts in the U.S., Canada, and Mexico until the middle of March. They join a long list of major automakers, including Ford, Honda and Fiat Chrysler, which have warned investors or slowed vehicle production because of the chip shortage. But it’s not just the automotive industry that’s struggling to get enough semiconductors to build their products. AMD and Qualcomm, which sell chips to most of the top electronics firms, have noted the shortage in recent weeks. Sony blamed the chip shortage for why it’s so hard to get a PlayStation 5 game console. Chips are likely to remain in short supply in coming months as demand remains higher than ever. The Semiconductor Industry Association said in December that global chip sales would grow 8.4% in 2021 from 2020′s total of $433 billion. That’s up from 5.1% growth between 2019 and 2020 -- a notable jump, given how large the absolute numbers are. Semiconductors are in short supply because of strong demand for electronics, shifting business models in the semiconductor world that created a bottleneck among outsourced chip factories, and effects from the U.S. trade war with China that started under former President Trump.

How 401(k) Plans Work And Why They Killed Pensions

March 28, 2021

Here is the link. 

Since 1980, pensions plans have been phased out in favor of 401(k) plans. They now represent nearly one-fifth of the U.S. retirement market. So how did 401(k) plans become such a popular form of retirement savings and how should they be used? Watch the video to find out.

Will NYC Go Bankrupt?

March 28, 2021

Here is the link. 

Mass unemployment, colossal bankruptcies, and a shattered tourism industry have ravaged New York City during the coronavirus pandemic. In January 2021, Governor Andrew Cuomo proposed raising taxes on the wealthy, while cutting Medicaid and school spending to balance the multi-billion dollar budget deficit. Opponents say tax hikes could lead to a mass exodus of the wealthy New Yorkers who fund a large portion of the city’s revenue. Others say that the crisis has exasperated existing inequalities and cutting social services will only hurt those most affected.

Weight control | 204 lb | no red meat | more exercise | tennis sports

March 28, 2021

Introduction

It is time for me to control weight. I should make this weight control project as my highest priority. No matter what I like to invest on stock market, main purpose is to have a happy life, and most of important is to stay fit and prevent healthy issues by controlling weight. 

10 ideas

I can come out ideas to avoid red meat, and control portion of meal and make myself stay hunger between meals. 

I also like to go out more often to play tennis sports, as soon as I get off from the work, I should stay on tennis court for one or two hours every day. 

Gary Dickerson Keynote – AI Design Forum™ 2019

March 27, 2021

Here is the link. 

During his keynote at the AI Design Forum™, Applied Materials CEO Gary Dickerson showed the audience how AI represents the biggest opportunity and challenge of our lifetime.

View from the Top: Gary Dickerson, Applied Materials

March 27, 2021

Here is the link. 

Gary Dickerson, president and CEO, Applied Materials Inc., speaks about "Navigating the Perfect Storm – A New Semiconductor Playbook for the AI Era" This Berkeley Engineering View from the Top lecture was delivered Tuesday, March 12, 2019, in Banatao Auditorium, Sutardja Dai Hall.

Gray stock: Graybug Vision - Innovation Showcase at Ophthalmology Innovation Summit @ AAO 2019

March 27, 2021

Here is the link. 

Fred Guerard, CEO speaks for Graybug Vision during the Innovative Showcase at OIS@AAO 2019. REGISTER for our next ophthalmology conference today http://bit.ly/2yFA6cv​.

Delisting Chinese Stocks? Why NIO, XPEV, LI, VIPS, IQ, TME Stocks Are Down Today

 Chinese stocks are making headlines today. Today’s news that the U.S. Securities and Exchange Commission has adopted measures to delist certain Chinese stocks is big.

Source: Engineer studio / Shutterstock.com

This comes in the wake of a series of U.S.-China talks in recent days. Let’s just say, these talks haven’t gone well.

As both countries form their hardline stances, it appears a wide swath of Chinese companies listed in the U.S. could be under pressure for some time. Accordingly, today’s selling in stocks like Nio (NYSE:NIO), Xpeng (NYSE:XPEV), Li Auto (NASDAQ:LI), Vipshop Holdings (NYSE:VIPS), iQiyi (NASDAQ:IQ) and Tencent Music Entertainment (NYSE:TME) isn’t unexpected.

Let’s dive more into what the SEC is up to, and what this means for investors.

Delisting Chinese Stocks: All About the SEC

On Wednesday, the SEC adopted measures prescribed by the Holding Foreign Companies Accountable Act. This bill was initially signed into law by former President Donald Trump last year. The aim of this piece of legislation is to delist Chinese companies if such companies fail to meet American auditing standards over a period of time.

The act would also require these companies to disclose governmental affiliations. Indeed, it appears the SEC has been hard at work providing a framework for how this act would be implemented within the prescribed 90-day window. The process for identifying companies that meet this standard is being reviewed, and public comments have been requested.

优质的成长股 | 2020年的那种投资思维 | 在牛市中亏得血本无归 | 市场往往就是这么残酷

 二线成长股今年能不能回到原来的历史高位，这可能也是相当不确定的一件事。以特斯拉来说，900美元的特斯拉本身就泡沫巨大，因为有很大一部分涨幅是因为ARK和木头姐的光环，进入标普500指数和拆股的炒作，还有马斯克炒作比特币后的散户狂欢，这些涨幅都和基本面没什么关系，自然终究要回归到理性。

历史从来都是惊人的相似，特斯拉未来很长一段时间，将进入一个业绩不断增长，股价不断下跌的过程。因为当一切的想象力和故事落实的时候，市场可能会发现，特斯拉似乎并没有那么优秀。正好比，木头姐认为特斯拉会在自动驾驶市场一家独大，会占据高端电动车市场90%的份额，会实现40%的保险利润率，并用这些逻辑得出了特斯拉应该价值3000美元。

这一切美好的故事，当前确实没办法被证伪，毕竟是5~10年后才会发生的事，机构在市场极度乐观的时候也愿意用这些预期进行炒作，但现实终究是现实，这些明显违背市场规律的结论，最终在未来都会被一一证伪，而那时将会是特斯拉跌下神坛的时候，所以股价想要回到历史新高，绝非一件易事。

回到那个问题，现在是不是熊市？我觉得这个根本不需要讨论，因为如果你仔细观察过去两周的标普热力图，你会发现，除了个别普跌的交易日，基本上每天都是超过80%的公司在涨，而标普和道指也就从高位回撤了1%左右。

一个股指不断上攻，即将创历史新高，并且80%公司都在暴涨的市场，显然得不出「进入熊市」的结论。事实上，这不仅不是熊市，我们反过来应该称之为「超级牛市」。毕竟整个2020年，也没见过市场有这么多公司在上涨的。

但问题也来了，为什么我们大家都亏钱了？这背后主要是因为选股问题。你买了一堆中概股，买了一堆ARK的成分股，没有买疫情复苏股，没有去买高增长的芯片股，没有跟随着市场的主线热点去投资，亏钱几乎就是必然的。

今年目前为止，很显然仍然是一个牛市，市场上的资金实在太多了，多到股市稍微跌一跌，马上就有无数人进去抄底，但确实也是一个不太容易赚钱的牛市，当市场80%公司都在暴涨的时候，我们反而却有很多人亏钱了。我一直强调一件事，那就是投资必须要有周期性思维。

拿AMD和INTC的股价涨跌来说，我们在过去一年都说INTC是垃圾，因为AMD的产品性能远比INTC要强，也抢走了INTC的很多市场份额，但进入到2021年，我们却更多让大家去买INTC，而不是去抄底AMD，因为AMD的产能受到了TSM的影响，市场份额被有生产能力的INTC反抢了回去。等到未来一天，TSM的产能复苏，那么我们又会让大家卖出INTC，再把AMD重新买回来。

这就是周期性思维，市场一直在变，你的投资理念也需要一直变化。2020年的疫情，价值股基本面因为疫情封锁彻底烂掉了，航空、游轮、赌场、能源这些板块腰斩的比比皆是。成长股则在疫情期间获得了高速发展，电商、SaaS、云计算这些板块翻倍股频出。

但到了2021年，这个市场完全变了。疫苗出来了，人们不要再居家隔离，旅游消费全面复苏，价值股板块在今年涨幅超过30%的比比皆是，而成长股则因为市场情绪的变化，美债利率的变化以及对未来增速放缓的担忧，纷纷跑输大盘，仅剩下芯片板块一棵独苗。

这并不是一次简单的板块轮动，而是一个投资主线的周期变动。经济复苏是至少未来一年的投资主线，如果你还抱着2020年的那种投资思维，以为持有优质的成长股就可以跑赢大盘，最终的结果很可能就是在牛市中亏得血本无归，市场往往就是这么残酷。

现在的牛市更加考验选股能力，你做好准备了吗？

二线成长股 | window dressing | TSLA | 芯片、消费、基建 | 强势板块

 二线成长股能不能买？这是很多朋友当前非常关心的一个问题，毕竟大多数亏钱就是因为买了这些公司。我很负责任的告诉你，现在并不是买入时机，这背后主要有三点原因：1、美债收益率仍然在高位，对成长股的估值造成了一定压力；2、纳指没有突破13600阻力线，随时有可能暴跌；3、成长股现在泡沫仍然巨大，还不够便宜。

从投资的角度，现在是季度末的最后几天，每当这个时候基金机构因为调仓，就会出现明显的强者恒强，这被资本市场称为window dressing效应。说的通俗点，机构会卖出一些弱势股，追涨一些强势股，再给客户吹牛逼的时候，就显得账面上好看点，毕竟那些跌很多的公司，我这没买嘛。

所以二线成长股在4月到来之前，相信都很难有会什么真正的行情，机构可能更多会愿意追涨芯片、消费、基建这些目前的强势板块。二线成长股想要王者回归，可能还需要一些新的变量出现，例如新的财报季交出一份让市场振奋的成绩单。在此之前，它们仍然不会有什么好的行情。

二线成长股今年能不能回到原来的历史高位，这可能也是相当不确定的一件事。以特斯拉来说，900美元的特斯拉本身就泡沫巨大，因为有很大一部分涨幅是因为ARK和木头姐的光环，进入标普500指数和拆股的炒作，还有马斯克炒作比特币后的散户狂欢，这些涨幅都和基本面没什么关系，自然终究要回归到理性。

芯片公司 | ASML, AMAT, LRCX, TSM, KLC | MU, INTC, SWKS | 周五王者回归 - March 26, 2021

 毫无疑问，科技股的风险很高。我在上周的文章里面提到了一个观点，那就是现在纳指在没有突破13600之前，如果你想持有科技股，那只能买芯片板块。

这个观点差不多整整说了四周时间，这一周再次得到了很好的印证。ASML、AMAT、LRCX、TSM、KLC这些芯片公司纷纷暴涨，MU、INTC、SWKS也在周五王者回归，不少芯片公司甚至在纳指这一轮大幅震荡的过程中，股价还创下了历史新高。

背后的逻辑再次强调下，芯片是唯一在后疫情时代加速增长的赛道，而电商、SaaS、社交媒体、移动支付等去年的明星板块，势必会面临增速放缓的困境，而在美债收益率持续上涨的当下，这些板块自然会面临杀估值的窘境。

有一个数据非常有意思，那就是最后一小时的成交量。金融博客零对冲早在2013年就发现，美股如果遭受大跌，往往在交易时段的最后半小时会出现“救火队”，大量买盘会奔涌而至，从而挽救美股跌势。这种“救市”现象被称为“3:30 pm Ramp Capital”，称如果在美东时间3:30买入标普500期货，然后在当天收盘时卖出，胜率极高。

但在过去3个月里，有29天美股都在最后一小时下跌。这3个月内，虽然标普500指数仍在奔向史上最高水平，但“累积最后一小时指标”(Cumulative the Last Hour Indicator)创下了1997年以来最大3个月跌幅。这种现象的严峻在于，上一次这种背离出现是去年3月新冠疫情导致股市暴跌时，这或许是值得我们警惕的地方。

二线成长股 | SE, SQ, CRWD, SHOP, ROKU

 从投资者的角度，这是一次惨烈但是也经典的爆仓，体现了人性之贪婪，市场之狂暴，以及风控体系和原则的重要性。每当这个时候，往往大家才能想起我反复提醒的那三句话：远离杠杆，远离做空，远离中概股的重要性……

我们见多了股神，但真正的股神，却永远是那个喜欢喝可乐的老头。

我这里也是想再次说下，大家炒美股的话，能别碰中概股就别碰了吧，尤其是今年这样一个中美双方充满火药味的市场，中概股的风险很大。另外SE、SQ、CRWD、SHOP、ROKU等二线成长股也从高位跌很多了啊，你抄底这些公司，难道不香吗？

群里面有位朋友就问了这么一个问题，「现在是不是熊市来了？」。这是一个非常有意思的问题，最近一段时间大家投资最痛苦的事，指数没怎么跌，但自己持有的个股跌的惨不忍睹。以纳指来说，其实这周也就回调了0.58%，但很多朋友持有的个股单周跌幅超20%的比比皆是。二线成长股继续大幅下挫，如果买的是中概股，那么单周腰斩的都出现了好几个。

March 27 2021 | China stocks - TME | 50% loss

 周五最大的事，某个对冲基金因为买了雾芯科技爆仓，被迫清仓了百度、爱奇艺、腾讯音乐和唯品会这几家中概股，那跌的叫一个惨，短短几天就实现了腰斩的目标。再加上周五的在线教育利空，跟谁学、好未来和新东方集体暴跌，投资中概股真的很让人绝望。

GSX - 跟谁学, $142 -> $39

Gray stock: technical analysis

 

钱宗琦 09:59

@Julia chen  不发图了。这是个“萝卜头”, 找不到脖子。周线还有下跌的迹象，但日线已开始现底。有几个数据供参考：1. $11 是近期的高点，如果波段操作，接近高点可卖出部分。2. $7-8.5是筹码密集区，大约有10M筹码，因此短期可能难突破$8.8, 但 $5.7 到 $8.8 也还有很大的空间。3. 这是个萝卜头，不知道根在哪？ 还会往下掉多少？但有10m 码在$7 以上， 如果是好公司有信心，是开仓的好机会。4. 如果已重仓，这种情况最好做右侧交易，等落到底(第一腿)，开始反弹再操作。比如到 $8.5 附近减仓卖出，回落后(第二腿)再补回来拉低成本以利长期持有。有了第一腿的底做参考，就可判断第二腿底的大概位置以便买入。一般第二腿比第一腿短。如果更长就要小心，表明可能会跌得更深。

陈建敏 10:08

@钱宗琦 太谢谢您了。我去年押6万加元石油股。一直跌, 我不会技术分析, 割肉了。结果hse.to 被cve.to 收购。

hse.to 翻倍。股市新手一定要学会注重价值而不是价格。再低有价值都会涨回去。价格华尔街说了算, 想赚钱自己

认真学习。虚心请教。

Actionable items

1. $7 - $8.5, 10 M shares 
2. $8.8 is hard to break through $8.8
3. $5.7 to $8.8 - biggest space 
4. What is bottom? We do not know. 
5. 10 million is above $7 share
6. If it is a good company, then it is time to build some positions

GRAY stock: technical analysis

 WeChat group "❤️❤️美股投资兴趣群2❤️❤️" chat history

Inbox

2489976605	10:13 AM (33 minutes ago)
to me

Dear:

The chatting history for this WeChat group "️️美股投资兴趣群2️️" is shown below.

————— 2021-03-27 —————

钱宗琦 09:59

@Julia chen  不发图了。这是个“萝卜头”, 找不到脖子。周线还有下跌的迹象，但日线已开始现底。有几个数据供参考：1. $11 是近期的高点，如果波段操作，接近高点可卖出部分。2. $7-8.5是筹码密集区，大约有10M筹码，因此短期可能难突破$8.8, 但 $5.7 到 $8.8 也还有很大的空间。3. 这是个萝卜头，不知道根在哪？ 还会往下掉多少？但有10m 码在$7 以上， 如果是好公司有信心，是开仓的好机会。4. 如果已重仓，这种情况最好做右侧交易，等落到底(第一腿)，开始反弹再操作。比如到 $8.5 附近减仓卖出，回落后(第二腿)再补回来拉低成本以利长期持有。有了第一腿的底做参考，就可判断第二腿底的大概位置以便买入。一般第二腿比第一腿短。如果更长就要小心，表明可能会跌得更深。

陈建敏 10:08

@钱宗琦 太谢谢您了。我去年押6万加元石油股。一直跌, 我不会技术分析, 割肉了。结果hse.to 被cve.to 收购。hse.to 翻倍。股市新手一定要学会注重价值而不是价格。再低有价值都会涨回去。价格华尔街说了算, 想赚钱自己认真学习。虚心请教。

System design: Case study | Delivery app

March 26, 2021

Here is the link. 

软件架构设计实战

andy

关注

发布于: 2021 年 01 月 10 日



背景：



• 通达是某上市公司全资投资成立的一家物流快递公司，主要进行同城快递业务，公司刚刚成立，组建 20 人技术部门，准备两个月后系统开发完成上线，你是后端架构师，请你完成系统顶层架构设计，并组织架构评审会议。



说明：技术部没技术负责人，由产品负责人兼管（产品负责人为原某互联网大厂的产品总监，研发出身），架构师（你）是技术部最资深的技术人员。



产品需求：



• 用户通过 app 发起快递下单请求并支付

• 快递员通过自己的 App 上报自己的地理位置，每 30 秒上报一次

• 系统收到快递请求后，向距离用户直线距离 5km 内的所有快递员发送通知

• 快递员需要进行抢单，第一个抢单的快递员得到配单，系统向其发送用户详细地址

• 快递员到用户处收取快递，并记录到系统中：已收件

• 快递员将快递送到目的地，并记录到系统中：已送达



说明：预计上线后三个月日单超过 1 万，一年日单超过 50 万



技术方案建议：



• 用户下单请求通过负载均衡服务器分发给下单网关集群

• 使用消息队列向 5km 内的快递员发送通知（消费者服务器获取的消息内容包括：用户地址，快递员列表）

• 快递员实时位置缓存在分布式缓存 Redis 中

• 数据存储使用 MySQL，第一个上线版本不要求做数据分片，但要做主从复制



说明：以上技术方案建议是公司请的外部技术顾问（该顾问是产品负责人的朋友）给出的，具体是否合适请架构师自己定夺



练习要求：



以 PPT 方式输出系统概要设计（顶层架构设计），包含以下模型，进行架构设计评审：



• 系统关键用例图，描述产品主要功能需求

• 下单抢单场景的业务活动图，角色领域泳道模型（角色：用户，快递员，系统）

• 系统部署模型：描述系统服务器关系（如：网关服务器，微服务服务器，负载均衡，分布式缓存，消息队列服务器，消息消费者服务器，数据库读写分离）

• 下单抢单场景的服务器时序模型

• 订单状态图模型