BC TECH
Saved by @SteveeRogerr

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
Santiago
@svpino
Interviews aren't only about technical skills.

Here are some questions to help you prepare.

🧵👇

Explain what you have been working on for the past few weeks.

What are the most exciting parts about that work?

What portion of it do you consider boring and why?

[2 / 10]

What specific libraries and frameworks are you familiar with?

What's the minimum set of libraries and frameworks that you'd recommend to any practitioner?

[3 / 10]

What kind of problems have you worked on in the past?

Can you list the specific use cases related to each one of these?

[4 / 10]

What is the most exciting project you have ever worked on?

What was your role and responsibilities on that project?

Why do you think your work on that project was important?

[5 / 10]
LIFE
Santiago
Santiago
@svpino
11 key concepts of Machine Learning.

— Supervised Learning Edition —

🧵👇

😜

Before starting, remember that, if you follow me, one of your enemies will be immediately destroyed (and you'll get to read more of these threads, of course.)

And if you don't follow me, well, you just hurt my feelings.

😜

1. Labels

(Also referred to as "y")

The label is the piece of information that we are predicting.

For example:

- the animal that's shown in a picture
- the price of a house
- whether a message is spam or not

👇

2. Features

(Also referred to as "x")

These are the input variables to our problem. We use these features to predict the "label."

For example:

- pixels of a picture
- number of bedrooms of a house
- square footage of a house

👇

3. Samples

(This is also known as "examples.")

A sample is a particular instance of data (features or "x.") It could be "labeled" or "unlabeled."

👇
MACHINE LEARNING
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Santiago
Santiago
@svpino
Here is a simple example of a machine learning model.

I put it together a long time ago, and it was very helpful! I sliced it apart a thousand times until things started to make sense.

It's TensorFlow and Keras.

If you are starting out, this may be a good puzzle to solve.


The goal of this model is to learn to multiply one-digit
TECH
Santiago \U0001f1fa\U0001f1f8\U0001f1fa\U0001f1e6
Santiago 🇺🇸🇺🇦...
@svpino
You are building a binary classification model to determine whether a picture shows a hot dog or not.

Which of the following activation functions is a good candidate for the output layer?

1. Rectifier Linear Unit (ReLU)
2. Leaky ReLU
3. Sigmoid
4. Softmax

Think about it.

The answer:

You could use either Sigmoid or Softmax.

I'm sure most of you picked Sigmoid. It's certainly the best way to approach this problem.

But Softmax is also an option —although unconventional for a binary classifier.

How about the other choices?

ReLU returns its input if positive, zero otherwise. Leaky ReLU is based on ReLU but with a slight slope for negative values.

ReLU and Leaky ReLU will always give us the previous layer output with no modifications if the input is always positive.

This doesn't help us.

Sigmoid has the ability to squash its input into a range that goes from 0 to 1.

This is good because we can now set a specific threshold for the output of a binary classifier.

Here is an example.

Any image with an output equal to or under 0.5 doesn't show a hot dog. Any image with an output above 0.5 shows a hot dog.

Sigmoid makes it very easy.

How about Softmax?
ALL
Santiago
Santiago
@svpino
20 machine learning questions that will make you think.

(Cool questions. Not the regular, introductory stuff that you find everywhere.)

🧵👇

1. Why is it important to introduce non-linearities in a neural network?

2. What are the differences between a multi-class classification problem and a multi-label classification problem?

3. Why does the use of Dropout work as a regularizer?

👇

4. Why you shouldn't use a softmax output activation function in a multi-label classification problem when using a one-hot-encoded target?

5. Does the use of Dropout in your model slow down or speed up the training process? Why?

👇

6. In a Linear or Logistic Regression problem, do all Gradient Descent algorithms lead to the same model, provided you let them run long enough?

7. Explain the difference between Batch Gradient Descent, Stochastic Gradient Descent, and Mini-batch Gradient Descent.

👇

8. What are the advantages of Convolution Neural Networks (CNN) over a fully connected network for image classification?

9. What are the advantages of Recurrent Neural Networks (RNN) over a fully connected network when working with text data?

👇
ALL , MACHINE LEARNING

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Jonas L
Jonas L
@jonasLyk
Wanna disable Defender when enabled Isolated Core and Tamper protection?

Its a bit more trouble- but doable, without ruining Isolated Core/Secureboot etc.

Defenders process will run as a unkillable protected service- so new tricks needed.

Here we go:

Ok- tamper protection is easy, just make .bat - run as adm:
:again
reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WdFilter\Instances\WdFilter Instance" /v altitude /t REG_SZ /d -1 /f
goto again

Then unload minifilter with process hacker:


The registry key will be changed while the minifilter do not protect it, when tamper protection makes the driver load again it cannot attach to volumes nor protect registry keys.

Removing it will make it recreate, but invalid altitude do the trick

Notice now the service is: Protected light(antimalware)
Now we cant do anything to the service/process- not even see its open handles.


Lets start by elevating to SYSTEM- just launch a command prompt, then close process hacker- and run it again from the command prompt.
Now process hacker runs as SYSTEM
INTERNET , TECH
Tinker \u274e
Tinker ❎
@TinkerSec
Singing the Blues:
Taking Down an Insider Threat

"I had all of the advantages. I was already inside the network. No one suspected me. But they found my hack, kicked me off the network...

...and physically hunted me down."


Many pentests start from the outside, wanting to see how the perimeter might be breached.

This pentest started from the inside. My client wanted to assume they had already been breached, and, if breached, how far could an attacker go.

Could they stop me once I was inside?

So they snuck me in. Disguised me as a new employee. Gave me a work computer, an ID badge, an account in their system... hell, I even had a cubicle w/my assumed name on it.

The only person who knew who I really was was their CISO. Everyone else thought I was Jeremy in Marketing.

During most of the first morning, I completed onboarding, made introductions, and completed menial tasks.

But I had to act quick. I only had a week onsite. I had to hack their network while not raising suspicion.

So I set about it.

You have to understand... most "Internal Pentests" are straight forward. The hard part is breaching the network, but once you're inside, it's a target rich environment. End of Life computers, default passwords, everyone a Local Administrator...
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Greta Musk
Greta Musk
@GretaMusk
🚔 HUGE #Tesla SERVICE PROBLEMS THREAD🚔

You might remember my 3 prior threads on how
TESLA. TREATS. ITS. CUSTOMERS. LIKE. TRASH.

Here's the 4th installment.
@tomkeinan @jonsey_lisa @jwmooc @tchanpoker @bryanthediamond @EconomicManBlog
$TSLA $TSLAQ 1/22


Welcome to Greta's 4th edition of #Tesla customers getting used and abused. Because that's the Elon Musk way.
@coffeebreakls @KocgibiHarun @omaragha @JayGhahari
$TSLA $TSLAQ 2/22


"The best service is no service." - Elon Musk a.k.a. #SpaceKaren
@briansaziz @FarSha998899 @thinktankfour @Billoday1
#Tesla $TSLA $TSLAQ 3/22


These #Tesla customers represent just the very tip of the iceberg. They are ones who have Twitter, have decided to complain about their #TeslaServiceIssues publicly, and were found by yours truly.
@yanismydj @hajelatweets @AlanHeldman @francislongo5 $TSLA $TSLAQ 4/22


Dear #Tesla customers: In California, if your vehicle has been out of service for >30 days total, it's a lemon. You can get punitive damages and attorney's fees. Don't sit around and take Elon's abuse. @13arm13arm @cecimar12 @richardson_skip @shootinglee $TSLA $TSLAQ 5/22
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Got Got Need
Got Got Need
@Hudlen_
Thought I'd put a thread together of some resources & people I consider really valuable & insightful for anyone considering or just starting out on their @SorareHQ journey. It's by no means comprehensive, this community is super helpful so no offence to anyone I've missed off...

1) Get yourself on the official Sorare Discord group https://t.co/1CWeyglJhu, the forum is always full of interesting debate. Got a question? Put it on the relevant thread & it's usually answered in minutes. This is also a great place to engage directly with the @SorareHQ team.

2) Bury your head in @HGLeitch's @SorareData & get to grips with all the collated information you have to hand FOR FREE! IMO it's vital for price-checking, scouting & S05 team building plus they are hosts to the forward thinking SO11 and SorareData Cups 🏆

3) Get on YouTube 📺, subscribe to @Qu_Tang_Clan's channel https://t.co/1ZxMsQR1kq & engross yourself in hours of Sorare tutorials & videos. There's a good crowd that log in to the live Gameweek shows where you get to see Quinny scratching his head/ beard over team selection.

4) Make sure to follow & give a listen to the @Sorare_Podcast on the streaming service of your choice 🔊, weekly shows are always insightful with great guests. Worth listening to the old episodes too as there's loads of information you'll take from them.
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Mateusz Czeladka | Pla...
@matiwinnetou
(1) Some haters of #Cardano are not only bag holders but also imperative developers.

If you are an imperative programmers you know that Plutus is not the most intuitive -> (https://t.co/m3fzq7rJYb)

It is, however, intuitive for people with IT financial background, e.g. banks

(2)

IELE + k framework will be a real game changer because there will be DSLs (Domain Specific Languages) in any programming language supported by K framework. The only issue is that we need to wait for all this

(3) Good news is that the moment we get IELE integrated into Cardano, we get some popular langs. To my knowledge we should get from day one: Solidity and Rust, maybe others as well?

List of langs: https://t.co/0uj1eBfrYj, some commits from many years ago..

@rv_inc ?

#Cardano

(a) Last but not least, marketing to people with Haskell, functional programming with experience and decision makers in banks is a tricky one, how do you market but not tell them you want to replace them. In the end one strategy is to pitch new markets, e.g. developing world

(b) As banks realize what is happening they maybe more inclined to join - not because they would like to but because they will have to - in such cases some development talent maybe re-routed to Plutus / Cardano / Algorand / Tezos
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Five billionaires share their top lessons on startups, life and entrepreneurship (1/10)


10 competitive advantages that will trump talent (2/10)


Some harsh truths you probably don’t want to hear (3/10)


10 significant lies you’re told about the world (4/10)
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RISHI PINGALA:THE ANCIENT INDIAN SAGE DISCREDITED FOR HIS MAJOR CONTRIBUTIONS TO MATHEMATICS & PHI

Have you ever heard about,"The Golden Ratio"?
The Golden Ratio or Phi(Greek) is a mathematical ratio of nature. Mother Nature is the most exquisite artist in herself.


&Its this Phi she uses to create all the beauty in World.
If anyone uses this ratio correctly in their art,it can turn into a spell-binding piece of work.Such is the significance of'Phi'.But my thread isn't about it.Its about somethin called'Fibonacci Series'&who actually made it


Phi is related to Fibonacci series(0,1,1,2,3,5,8,13,21,34...)
&this series is responsible for everything dat is beautiful on this planet. Just try to calculate the ratio of any 2 successive numbers ÷ each of them by the number before it in above infinite series.

E.g. 3/2=1.5, 5/3=1.666, 8/5=1.6, 34/21=1.61904 and so on. Did you notice something? The ratio is coming almost same every time. This ratio is called 'Phi 'which is numerically represented as 1:1.618. This Golden Spiral is made in exact proportion of 1:1.618.


The thing I want to emphasize here is that we always find only those things appealing and attractive that have Phi. It's in our subconscious. Isn't it some revelation? We are the part of this Divine proportion of the God or the Mother Nature. Check these:
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Antonio García Martíne...
@antoniogm
Ok, I'll hop on this Elizabeth Warren/Native American testing bandwagon (gently and non-politically).

I've been a @23andMe customer for a while, and have followed their ancestry updates closely.

All is more or less as expected....except for this bit about Native American.


The family is almost completely composed of Spanish peasants (from various regions) who emigrated, along with a massive wave in the late 19th-cent./early 20th-cent., to Cuba back when it was a booming economy (richer than Spain's) and worth emigrating to (Communism killed that).

Also, the native population of Cuba was annihilated early on---was the first place the Spanish colonized after all. Having a native background in Cuba would be like having the same in, say, Massachusetts, particularly if you're (say) mostly Irish. Just really, really unlikely.

(Note: the North African/Arab background is less mysterious. The Iberian peninsula was part of the Muslim world for centuries. It would be odd *not* to have some Arab/Middle Eastern background coming from Spain. Given the family is mostly from Northern Spain, it's small though.)

I have a Spanish passport, have been back to the ancestral villages in Spain, seen the church where my grandmother was baptized, my grandfather told me stories about growing up as the child of Spanish colonists in rural Cuba. The native bit just clashes with all the family lore.
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Sri Devi Karumariamman mandir, Chennai, Tamilnadu

Sri Devi Karumariamman mandir is in Thiruverkadu, a suburb of Chennai. It is said that God Muruga came here and obtained the 'Vel' (spear) from His mother, Goddess Karumari (an avatar of Parvathi) 1/n


to fight the demon Suran and hence this place was called as 'Vel kadu' and became as Verkadu. As per legend Devi Karumariamman once disguised as a soothsayer visited Bhagwan Surya, the Sun God, to predict His future. 2/n


Not realising that the soothsayer is none other than Sakthi Matha, Surya ignored Her. Angered by his indifference, Devi Karumariamman immediately retreated. Bhagwan Surya lost His glory and the earth plunged into darkness. 3/n


Bhagwan Surya then realised His folly and pleaded forgiveness from Devi Karumariamman. In order to pacify mother Karumariamman, Suryadev said that His rays would fall on Her directly twice in a year and touch her feet. (in the month of Panguni (March- April) & during (Sep - Oct)


Mother Karumari Amman is worshipped here in two forms.A swayambu (self manifested) with only head visible above the ground and another one in a graceful sitting posture with all Parasakthi features,with four arms holding skull, sword, trishul, udukkai (damru). 5/n
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sriram
sriram
@SriramKannan77
Swami Ramanujar:
Important personalities in Sri Ramanujas Life :
🌸ASURI KESHAVA SOMAYAJI-Father of Sri Ramanujar .Asuri keshava somayaji was a learned brahmana living in sriperumbudur.


🌸KANTHIMATHI-Mother of Sri Ramanuja. Kanthimathi was the sister of sri periya thirumalai nambi .
🌸SRI YAMUNACHARYA-Acharya of Sri Ramanuja.Also known as Alavandar.
🌸THIRUKOKOSHTIYUR NAMBI-Also known as Ghosti Purna.He instructed the Rahasya Traya to Sri Ramanujar.

He lived in thirukoshtiyur.
🌸THIRUKKACHI NAMBI-Kanchi purna was born in puvirunthavalli near kanchipuram and met the young ramanuja at an important time.He did the service of Lord Varadha.

🌸THIRUVARANGA PERUMAL ARAIYAR-Important acharya lived in srirangam and rendered the service of playing music for lord Sriranganatha.

🌸PERIYA THIRUMALAI NAMBI-He was the maternal uncle of Sri Ramanuja.He taught sri ramanuja about the epic of sri ramayana and other ithihaas and puranas.Served sri venkateswara at tirumala.
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