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Santiago
@svpino 3 years, 3 months ago 508 views

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11 short programming problems to stretch your imagination and make sure you are staying on your toes.

(Starting with the simple ones, they get more fun as you move towards the end.)

🧵👇

1. Write a function that reverses an array in place.

In other words, the function should not use an auxiliary array to do the work.

2. Write a function that finds the missing number in an unsorted array containing every one of the other 99 numbers ranging from 1 to 100.

3. Write a function that finds the duplicate number in an unsorted array containing every number from 1 to 100.

Only one of the numbers will appear twice.

4. Write a function that removes every duplicate value in an array.

There could be more than one value duplicated. You should remove all of them leaving a single copy of the value.

5. Write a function that finds the largest and smallest number in an unsorted array.

6. Write a function that finds a subarray whose sum is equal to a given value.

7. Write a function that finds the contiguous subarray of a given size with the largest sum.

8. Write a function that, given two arrays, finds the longest common subarray present in both of them.

9. Write a function that, given two arrays, finds the length of the shortest array that contains both input arrays as subarrays.

10. Write a function that, given an array, determines if you can partition it in two separate subarrays such that the sum of elements in both subarrays is the same.

11. Write a function that, given an array, divides it into two subarrays, such as the absolute difference between their sums is minimum.

I'd love to see some answers!

If you want more content on software engineering, machine learning, and adjacent topics, give me a follow. I post threads like this every week. You can enjoy more of this content here: @svpino.

More from Santiago

Santiago
@svpino

10 machine learning YouTube videos.

On libraries, algorithms, and tools.

(If you want to start with machine learning, having a comprehensive set of hands-on tutorials you can always refer to is fundamental.)

🧵👇

1⃣ Notebooks are a fantastic way to code, experiment, and communicate your results.

Take a look at @CoreyMSchafer's fantastic 30-minute tutorial on Jupyter Notebooks.

https://t.co/HqE9yt8TkB

2⃣ The Pandas library is the gold-standard to manipulate structured data.

Check out @joejamesusa's "Pandas Tutorial. Intro to DataFrames."

https://t.co/aOLh0dcGF5

3⃣ Data visualization is key for anyone practicing machine learning.

Check out @blondiebytes's "Learn Matplotlib in 6 minutes" tutorial.

https://t.co/QxjsODI1HB

4⃣ Another trendy data visualization library is Seaborn.

@NewThinkTank put together "Seaborn Tutorial 2020," which I highly recommend.

https://t.co/eAU5NBucbm

Santiago
@svpino

What's machine learning?

Not a framework. Not a different language. Not the latest "cool" thing around the Internet.

Thread: Let me convince you that machine learning is the best thing since sliced bread 🍞.

Let's start with a simple exercise:

"Write a function that returns 0 if a supplied number is even or 1 if the number is odd."

If you are a developer, I'm sure you know how to write this function. It should be simple, right?

To avoid using a specific syntax, let's represent this function as follows:

y = f(X)

Where:
• X → The input number
• y → The result (0 if even, 1 otherwise)
• f → The function that does the work

We can now get to the interesting part.

If you are a programmer, writing this function is simple.

You know the relationship between X (the input number) and y (the output), so you can easily write the rules (the function.)

In machine learning, we don't write the rules. We learn them.

Imagine we had an algorithm that processes many samples (X → y), learns the relationship between them, and comes up with the correct rules.

We call these samples "training data," and they would like like this:

• 2 → 0
• 5 → 1
• 8 → 0
• 4 → 0
• 3 → 1
• ...

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Santiago
@svpino

My recommendation to start learning how to deal with structured data: Kaggle's Pandas Tutorial.

• Creating, Reading, Writing
• Indexing, Selecting, Assigning
• Summary Functions, Maps
• Grouping, Sorting
• Data Types, Missing Values
• Renaming, Combining

100% Python 🐍.

Santiago
@svpino

My recommendations to start with machine learning math:

• Statistics 110: Probability — Harvard University
• Essence of Linear Algebra — 3Blue1Brown
• Multivariate Calculus — Coursera

Links and 3 additional free resources here: https://t.co/fEmpmRKEvJ

If you are looking for more machine learning content, give me a follow and I’ll keep your feed interesting 😉.

Santiago
@svpino

For a long time, I didn't understand how to use Virtual Environments in Python 🐍.

If this is just, let's end it here and now: 🧵👇

[2] Virtual Environments let you deal with the dependencies that your code has with external Python libraries.

It avoids having conflicts when your projects depend on different versions of the same library.

👇

[3] Let's imagine that you are building your first Python project and you install the "requests" library:

pip install requests

You get version 2.24.0 installed in your system.

👇

[4] A month later, you decide to work on your second project. It also needs the "requests" library.

But the latest version is not 2.24.0 anymore.

Now version 3 is available, and that's the one you want to use!

👇

[5] You could upgrade your entire system to version 3, but then you'll be potentially breaking the first project you built that depends on 2.24.0!

Can you imagine this happening on a server with many more applications running?

👇

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Neil S W Murray
@neilswmurray

1) Looking back on my "career" with @TheNordicWeb over the last 5 years, in retrospect it's easy for me to join up the dots and make sense of the journey:

#cphftw #sthlmtech #helyes 🇩🇰🇫🇮🇮🇸🇳🇴🇸🇪

2)

- Join & start community initiatives to meet people
- Learn from these people about how special the Nordic tech scene is
- Share this with the world through The Nordic Web
- Realise the real value is in the data, particularly in building network
- Use network to raise a fund

3) In fact, it looks all very strategic, but the reality is anything but.

My lack of vision and goals during this 5 year period was _criminal_

Any movement from one step to the next was never pre-planned and was instinctive, or worse, accidental.

4) While I am embarrassed to think of my headless chicken self, there's also part of me that thinks that none of this would have turned out where it did if I had of been deliberate and strategic about this.

5) In fact, I think my genuine love for the Nordics and the ecosystem is the MAIN reason to explain how I raised my fund & managed to move from step to step.

My story is a good example of how passion can be more powerful than strategy in the early stage of an idea/company.

EverythingOppresses
@SoOppressed

The first area to focus on is diversity. This has become a dogma in the tech world, and despite the fact that tech is one of the most meritocratic industries in the world, there are constant efforts to promote diversity at the expense of fairness, merit and competency. Examples:

USC's Interactive Media & Games Division cancels all-star panel that included top-tier game developers who were invited to share their experiences with students. Why? Because there were no women on the

ElectronConf is a conf which chooses presenters based on blind auditions; the identity, gender, and race of the speaker is not known to the selection team. The results of that merit-based approach was an all-male panel. So they cancelled the conference.

Apple's head of diversity (a black woman) got in trouble for promoting a vision of diversity that is at odds with contemporary progressive dogma. (She left the company shortly after this

Also in the name of diversity, there is unabashed discrimination against men (especially white men) in tech, in both hiring policies and in other arenas. One such example is this, a developer workshop that specifically excluded men: https://t.co/N0SkH4hR35

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Zen Black
@z3nblack

1/ Thread: "A Silicon Valley Ponzi Scheme"

Thanks to @chamath for laying this out in Social Capital's 2018 annual letter.

I've always appreciated his outspokenness.

2/ The hardest thing for most startups today is the path to market: first finding product-market fit & a way to reach customers, then building a ruthless machine to acquire, monetize & retain them.

3/ Because of this, when the VC industry invests capital into fast growing startups today, the plurality (if not majority) of invested capital will go into user acquisition and ad spending, for better or worse— usually worse.

4/ Todays massive venture-backed advertising, sales, and user acquisition playbook has morphed into one that champions growth at any cost.

This is creating a big bill that will soon come due...

5/ Ad impressions and click-throughs are bid up to outrageous prices by startups flush with venture money, and prospective users demand more and more subsidized products to gain their initial attention.

Colby Fayock
@colbyfayock

Next.js has taken the web dev world by storm

It’s the @reactjs framework devs rave about praising its power, flexibility, and dev experience

Don't feel like you're missing out!

Here's everything you need to know in 10 tweets

Let’s dive in 🧵

Next.js is a @reactjs framework from @vercel

It couples a great dev experience with an opinionated feature set to make it easy to spin up new performant, dynamic web apps

It's used by many high-profile teams like @hulu, @apple, @Nike, & more

https://t.co/whCdm5ytuk

@vercel @hulu @Apple @Nike The team at @vercel, formerly Zeit, originally and launched v1 of the framework on Oct 26, 2016 in the pursuit of universal JavaScript apps

Since then, the team & community has grown expotentially, including contributions from giants like @Google

https://t.co/xPPTOtHoKW

@vercel @hulu @Apple @Nike @Google In the #jamstack world, Next.js pulled a hefty 58.6% share of framework adoption in 2020

Compared to other popular @reactjs frameworks like Gatsby, which pulled in 12%

*The Next.js stats likely include some SSR, arguably not Jamstack

https://t.co/acNawfcM4z

@vercel @hulu @Apple @Nike @Google The easiest way to get started with a new Next.js app is with Create Next App

Simply run:

yarn create next-app

or

npx create-next-app

You can even start from a git-based template with the -e flag

yarn create next-app -e https://t.co/JMQ87gi1ue

https://t.co/rwKhp7zlys

Knarf
@Knarf93

@zkat__ I'm in the position that I actually find npm / yarn the best ecosystem. Whenever I use something else I always end up stubbing my toe into something thats missing / feels wrong.

Ex. Cargo seems to neither have a concept of devDependencies nor peerDependencies.

I also can't understand why it wouldn't have an "add" command to add a new dependency. And I'm no fan of Toml, json is greate (easy to parse and build tooling around), and the better option in my opinion would be json5.

C / C++ seems to just not have language package managers. The linux / bsd crowd seem to have decided that the system package manager also should be the language package manager. Which might have been fine if every Linux distro used the same system package manager.

Instead we end up with a N x M problem. Where we have a bunch of different operating systems and they all support multiple system package managers. So there's no easy way of distributing, referencing and updating C / C++ packages.

It is also my opinion that the compiler / runtime should be a package dependency. I don't like Rust's split between rustup and cargo (they should have been one tool). Similarly it would be better if you added Node as a dependency to package.json, that way we wouldn't need NVM.

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Rudy Havenstein, liste...
@RudyHavenstein

I hate when I learn something new (to me) & stunning about the Jeff Epstein network (h/t MoodyKnowsNada.)

Where to begin?

So our new Secretary of State Anthony Blinken's stepfather, Samuel Pisar, was "longtime lawyer and confidant of...Robert Maxwell," Ghislaine Maxwell's Dad.

"Pisar was one of the last people to speak to Maxwell, by phone, probably an hour before the chairman of Mirror Group Newspapers fell off his luxury yacht the Lady Ghislaine on 5 November, 1991." https://t.co/DAEgchNyTP

OK, so that's just a coincidence. Moving on, Anthony Blinken "attended the prestigious Dalton School in New York City"...wait, what? https://t.co/DnE6AvHmJg

Dalton School...Dalton School...rings a

Oh that's right.

The dad of the U.S. Attorney General under both George W. Bush & Donald Trump, William Barr, was headmaster of the Dalton School.

Donald Barr was also quite a

Donald Barr had a way with words. pic.twitter.com/JdRBwXPhJn
— Rudy Havenstein, listening to Nas all day. (@RudyHavenstein) September 17, 2020

I'm not going to even mention that Blinken's stepdad Sam Pisar's name was in Epstein's "black book."

Lots of names in that book. I mean, for example, Cuomo, Trump, Clinton, Prince Andrew, Bill Cosby, Woody Allen - all in that book, and their reputations are spotless.

Alex Stamos
@alexstamos

The entire discussion around Facebook’s disclosures of what happened in 2016 is very frustrating. No exec stopped any investigations, but there were a lot of heated discussions about what to publish and when.

The story doesn\u2019t say you were told not to... it says you did so without approval and they tried to obfuscate what you found. Is that true?
— Sarah Frier (@sarahfrier) November 15, 2018

In the spring and summer of 2016, as reported by the Times, activity we traced to GRU was reported to the FBI. This was the standard model of interaction companies used for nation-state attacks against likely US targeted.

In the Spring of 2017, after a deep dive into the Fake News phenomena, the security team wanted to publish an update that covered what we had learned. At this point, we didn’t have any advertising content or the big IRA cluster, but we did know about the GRU model.

This report when through dozens of edits as different equities were represented. I did not have any meetings with Sheryl on the paper, but I can’t speak to whether she was in the loop with my higher-ups.

In the end, the difficult question of attribution was settled by us pointing to the DNI report instead of saying Russia or GRU directly. In my pre-briefs with members of Congress, I made it clear that we believed this action was GRU.

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Vigilant AFA
@AfaVigilant

One fascist to watch in 2021 is Joseph Charles "Oakman" Golinske of SE MI. He's been a Proud Boy for a couple years, but took a break recently from the group and promotes himself through the "Oak Nation" channel on Telegram.

Most people may be familiar with him as the tall guy in the Proud Boys bridge shot, from their August 17, 2019 attack on Portland, which featured an American Guard bus trying (and failing) to bludgeon antifascists with hammers.

He was also with his g/f at the time (Dominique Tota, left of Tarrio), and that's definitely a twitter account folks will want to block/report because he posts on it.

He's been plenty active at the pro-Covid/anti-mask/ReOpen protests in Lansing MI, seen here with Jerry Wayne and an effigy of Gretchen Whitmer, who his militia friends tried to kidnap and publicly execute.

Outside of the Proud Boys, his solo "career" with Oak Nation features the same misogyny, classism and gateway to far-right domestic terrorism the Proud Boys themselves feature. Here's him peddling oxychlorinque and bragging about harassing service workers.

$KENYAN\U0001f1f0\U0001f1ea HISTORY\U0001f1f0\U0001f1ea$

KENYAN🇰🇪 HISTORY🇰🇪...
@historykenya101

Have you ever wondered why the sons and daughters of the colonial chiefs and guards who were collaborators live a good life while those of the MAU MAU fighters live in abject poverty?

***THREAD***

It should be known that the colonialists reached a point that they knew they had 2 leave Kenya since they couldn't handle the Mau Mau war & the world was moving toward accepting independent Africa.However,the colonialists devised an evil scheme that still eats Kenya upto this day

Under this scheme, the colonial state came up with a plan that saw the first crop of chiefly “big men” being empowered financially to take their children to schools and eventually have those children go to England for further studies...

...and eventually providing a ready-made socio-economic & political class whom state power could be entrusted in the post-colonial era.This explains why their children & grandchildren still hold majority of important positions in govt or in the private sector supported by state.

This also explains why children and grandchildren of these homeguards are always given preferential treatment when it comes to government appointments. Wewe na masomo yako you are always asking why you can never get a job in government...yet you're qualified..now you know.

Jig's Patel
@jigspatel1988

Thread on
"Intraday Banknifty Strangle based on OI data"

(System already shared, today just share few examples)
(1/n)

-Trade timing after 9:45

-Check Banknifty change in OI data at 9:45, and identify the highest OI built up in call side and put side

-We will sell both strikes with combined premium as SL on both legs.
(2/n)

28th June 2021

BN open-35440
At 9:45 trading at 35350
Highest OI in call side at 35500 CE and 35000 at put side
Strike selection 35500 CE- 35000 PE
(3/n)

29th June 2021

BN open-35323

At 9:45 trading at 35112

Highest OI in call side at 35300 CE and 35000 at put side

Strike selection 35300 CE (232) - 35000 PE (150) Combined premium 382 , Both legs SL 382
(4/n)

30th June 2021

BN open-35030

At 9:45 trading at 35002

Highest OI in call side at 35000 CE and 35000 at put side

Strike selection 35000 CE(176)- 35000 PE(213) Combined premium 389 , Both legs SL 389
(5/n)