A blind programmer and counterfeit coin

20 years ago I was very shortsighted -7 vs -14. The doctors of that time could not find the right glasses that I'd take to the cinema. A miracle saved me. I was one of the first patients of the Moscow center eye surgery EXCIMER, where in 1999 I had the surgery on vision correction using laser technology LASIK. Each eye cost a little more than $ 1,000. After the surgery I forgot about the glasses and was happy.
And happy, when suddenly the vision started to blur. In 2013 I went to see the puck, 2015 — a soccer ball (I play soccer and hockey 6 times a week) and I finally stopped to meet nice women. In the brain emerges the question — what, again?

Despite the Council Habra local doctor, whom we all know and respect, I decided to do a second operation for vision correction.

Of course, I chose EXCIMER, but not Moscow, Nizhny Novgorod and closer.

I had surgery on Friday the 13th. 350 euros for the eyes. Like 17 years ago, I became temporarily farsighted; the fact that after the surgery near vision comes back to normal mode immediately. Swelling and fog can disappear in 2 days, and it may for a month — it all depends on the individual who cut my eye.

What is farsightedness? When you can't read and write and lifestyle changes. Mostly listen, probe and ponder. Head climbs things, including math puzzles that are quite difficult to solve in mind.

One such puzzle is suddenly permanently stuck in my head. This is a riddle about a fake coin. Recall the problem statement —

The 12 coins and scale weights. It is known that one of the coins is fake, either lighter or heavier than the other.
How to find a fake coin in three weighings?

Once I have successfully solved this problem with a pencil on paper but not in the mind. Now I don't have the patience to sort through in the dark of consciousness all the options.

And I decided to write a simple app for iOS, simulating the conditions of the problem. Blind programming is a quest. How to write this article. But I coped with two keys CMD and +. At this point in time I can recognize the text on 27 inch monitor, if the screen holds no more than 18-20 rows. Clearly. With the keyboard also easy — the fingers remember, but often stray from familiar positions. The keys themselves I do not see, but Well i know the difference.

There was quite a lot of funny and tragicomic moments, and You could guess; but more importantly, I was able to escape from the twilight state of the soul.

The app, of course, completely insane, and the benefit it brought me. Including intellectually. The problem about false coin can now be solved with closed eyes, in different versions, with sequels, from left to right and top to bottom. By the way, it is still asked in interviews for admission to work.

A few words about the development life cycle. Initially I made one original level, repeating the conditions of the problem. Plenty marechausse, added levels 2, 3, 4, and so forth, the 11 coins. Even preschoolers have learned to solve simplified problems.

I thought it would be nice to add the levels in which we can solve the problem with probability not less than 0.5 and added 5 more levels with 13,14,15,16,17 th coins. Quickly passed the new frontier, I added an infinite number of levels in the framework of the 5 bit and calmed down. Calm down!

Specially for readers of Habra the game is free and is translated into Russian language.
Falshivomonetchik

All comments on the errors in the article will not send. Remember, I can't read them.

Of course, the article is a deliberate mathematical error, who found her — the real programmer, not like me.

Hope to see you soon!

Article based on information from habrahabr.ru