Tag: facebook

A very interesting lecture by Zhenya Timonova on ants and their views on life, termites, and naked mole-rats

https://youtu.be/OUI2DXdY9Bw

Fellow programmers, remind me how to transform the list

a=(3,4,5,8,10), b=(1,3,8,10), c=(4,10), d=(8,10)

into

a=(e,4,5), b=(1,e), c=(4,10), d=(8,10), e=(3,d)?

Actually, for this purpose:

https://github.com/raliev/rulegroupspoc/blob/master/sampleoutput.txt

There is a matrix of 1 million users by 100,000 products and a set of rules dictating which product is available to which user. I have already developed a fast algorithm (still unoptimized) that creates a Products x Usergroups matrix, and calculates user groups. Under certain conditions, there will be significantly fewer user groups than products, and each product could be associated with a list of user groups, instead of a list of users. However, in the calculated groups, there are repetitions that could further reduce the list of groups to be stored alongside the products. This is where substituting “e” from the example above comes into play. But how to do this efficiently? Assume that there are 100,000 users, less than 50,000 groups.

In the photo is the NASA OV1-8 PASCOMSAT satellite, 1966. This one specifically is inflatable, but engineers, let’s fantasize – what if you were tasked with creating a hollow sphere covered with regular polyhedra, how would you approach the task? Assume it needs to be assembled from pentagons and hexagons. Then, to manufacture pentagons and hexagons separately, one must calculate how many are needed including duplicates, compute the convex and concave features, devise a method for reliable connections, and organize molds for casting. And this is just to manufacture the sphere.

I know the answers to the questions above, just an interesting educational problem for interviews and to assess people’s thinking abilities) And the photo at NASA turned out a bit crooked).

Okay, simple question – how many pentagons are needed to cover a sphere with pentagons and hexagons? The calculation fits into one Facebook comment)

UPDATE: In short, the correct answer is 12. Grigory Bakunov did well) There is a beautiful theorem by Euler, stating that for any convex polyhedron, the number of vertices minus the number of edges plus the number of faces will always equal two. If our polyhedron consists of X hexagons and Y pentagons, then the number of faces will be X+Y, the number of vertices will be (6X+5Y)/3, and the number of edges – (6X+5Y)/2. Here, 5 and 6 represent the number of edges of a pentagon and a hexagon, respectively, and the denominator accounts for the fact that two edges of a flat figure form one edge of a volumetric one, and the same thing for vertices, only with a three. So now, plugging this into Euler’s formula, we find that X drops out of it completely, and Y=12. This means that to tile a sphere with pentagons and hexagons, exactly 12 pentagons are needed, while the number of hexagons can be as many as necessary. Furthermore, to apply this pattern onto a sphere, the flat faces need to be projected onto the spherical surface, where they will simply transform into an arc. To assemble the sphere, you will need 12 pentagons (all identical) and some number of hexagons. Their number depends on the size of the pentagons. This too can be calculated, but it would be rather lengthy.

We are selling Hodor’s autobiography

https://www.amazon.com/North-Winterfell-autobiography-Hodor/dp/1520400837

Somehow, I ended up reading the December issue of “Red Star”, just out of curiosity. People there speak in some strange language.

For example, in an article on the link, a guy is asked a rather specific question, “What should be our, or rather, your – Strategic Rocket Forces’ – response to the US deploying their missile defense systems in Eastern European countries?”. The response, when translated from this incomprehensible language into Russian:

“A number of measures have been developed to reduce the effectiveness of the USA and to accomplish the set objectives. These measures involve the creation of missile complexes. It is planned to develop scientific and technical groundwork and continue the efforts to create means of attack for the developing missile defense system” (I’m not lying, that’s exactly how it was written: “continue the work on creating means of fire and functional destruction of reconnaissance, control, and strike means of the developing missile defense system.”)

The printed version of the article contains two more paragraphs about nothing. Mentioning that inspections showed a high level of preparedness and everyone did a great job.

Let’s take another specific question. Journalist: (simplifying the question) In 2016 you mentioned that UAV models were not autonomous but controlled, which is bad. Is anything being done?

Answer: “Indeed, it required additional research. The research is being conducted successfully. The approval of the research results showed that most of it will be completed by next year.”

And so it goes there!

http://redstar.ru/nash-yadernyj-shhit-ostayotsya-nadyozhnym/

Done! Strava showed a total of 22:08 for 5K with an average pace of 4:41 or 23:24 for a 5K distance. I don’t understand why its total differs by 01:16… The screenshots show more for the entire distance because I turned off the tracker late, and I surely ran in zigzags. The official result is 24:06 / distance, 4:46/km. Apparently, the actual distance was more than 5K, including due to inevitable zigzags.

At work, they upgraded the fitness center, now you can run through the flooded meadows of Ireland on a Precor and socially pedal on a Peloton. I seem to have missed the moment when treadmills became so advanced. Recognizes me by the phone I left on the shelf. Darling.

Just can’t find a way to ride through the alpine meadows on a peloton. Is it just for classes? Does anyone know?

Hooray! Green card obtained! A journey of two years and two months and some amount of money. Now almost on normal terms in the USA. The family already celebrated it in December, but it kept not being sent to me, and because of this, I was also unable to leave the country from January (meaning, I could leave, but re-entering would be problematic). And finally, I got it 🙂 I wish my colleagues successful completion of their cases too, as I am the first swallow from our cozy group.

Does anyone know if there is a service something like an online NoSQL database where one can dump data from the front end of a website or some real-time system, which would quickly save it into an unlimited cluster, and then allow aggregation and reporting from it using a relatively simple programming language? Essentially, like Google Analytics but without the analytics, yet with the appropriate tools to write it? Supporting map/reduce, distributed processing, etc. The main feature here is a) not to host it yourself but in the cloud, b) pay only for resources, c) not to bother creating proprietary solutions and maintaining infrastructure.

Very interesting about the fish that creates sand paintings in search of a spouse. All episodes are available on Netflix. The video at the link is just a tiny piece (apparently, one of the most interesting) and each episode is 50 minutes long.

// BBC Earth, Life Story, Ep.5 Courtship