My answer to a young programmer

You maybe know that I offer C++ mentoring via Twitter (DMs are open!) and, as it happened, someone approached me and wanted to be mentored. So I asked him for his questions and then wrote some responses, which ended up to to be qute long... Then the idea to share what I wrote in this blog - maybe someonw will find it interesing.

Without much ado, to the questions.

1. Questions

I first asked about the goals. Thes answers are probably in line with many young programmers want:

1. I just need to be able to solve programming problems and strong myself in
this part, to be qualified for big tech companies interviews like Google,
Microsoft and Amazon. 

2. No the programming language doesn't matter for me, I know the basics of C, C++ and Python but I just want to be a problem solver and think like a programmer 

3.  I just want to understand the theory behind Algorithms and Data Structure

Then also came a list of resources that one finds on the internet using uncle Google. I won't show them here, as thea are quoted in the response.

2 The Response

Here's my response, in full, without any later editing:

Hi Xyz!

I had a look at your references:

>Courses:

>Algorithms and Data structures by Revi
>https://youtube.com/playlist?list=PLEbnTDJUr_IeHYw_sfBOJ6gk5pie0yP-0

Here we have much complexity theory but little of algos - only basic sorting methods.

>Algorithms by Abdul Bari
>https://youtube.com/playlist?list=PLDN4rrl48XKpZkf03iYFl-O29szjTrs_O

Don't know what to think about it's TOC - maybe too academic (too much about recurrences) but also covers a broad range of themes you'll need. So-so.

>MIT 6.006 Introduction to Algorithms
>https://youtube.com/playlist?list=PLUl4u3cNGP61Oq3tWYp6V_F-5jb5L2iHb

Had a look the TOC and liked it! If you can grasp these themes, you'll have good working knowledge of Comp.Sci.

>Books:

>Data Structures and Program Design in C by Robert L. Kruse
>https://goodreads.com/book/show/27846.Data_Structures_and_Program_Design_in_C

Looks like it's pretty old. Probably outdated, looks like waste of time.

>Introduction to Algorithms By Thomas H. Cormen
>https://mitpress.mit.edu/books/introduction-algorithms-third-edition

This is a classic, maybe a little heavy on the academic side, but a good reference to check what the options are. For an algorithms book the "The Algorithm Design Manual" by Steven Skiena is a much lighter read I'd recommed!

>Think Like a Programmer by V. Anton Spraul
>https://goodreads.com/book/show/13590009-think-like-a-programmer

I don't know this one. Had a look at the TOC and it can be OK or even good. It has a couple of programming problems but the title seems to be kind of a clickbait. Notheless. maybe it's good.

>Practice:

>https://hackerrank.com

Don't know this one (sorry) and couldn't check it out, as it requires a login. Back in the day Google recommended topcoder.com for testing your problem-solving skills in competitions, but I don't know the current status of it.

>https://leetcode.com

Don't know this one (sorry), but it looks somehow inetersting at first glance. You have specific questions for Google, Facebook, etc. Could be worth it.

And responses:

>I just need to be able to solve programming problems and strong myself in this part, to be qualified for big tech companies interviews like Google, Microsoft and Amazon.

A classic book for that is "Cracking the Coding Interview" by Gyle Laakmann McDowell - but it's a real tome! "Programming Interviews Exposed" by J. Morgan et. all was a lighte read. "Algorithms for Intreviews" by A. Aziz & A. Prakesh has many tough problems, but the solutions aren't that well explained - a challenge!

>Q1: No the programming language doesn't matter for me, I know the basics of C, C++ and Python but I just want to be a problem solver and think like a programmer

To be a (real) problem solver you need some deep knowledge in at leas one OO-langauge! Programmers think in patterns, you have to learn them by solving programming problems! On a little higher level, you'll need at least cursory knowledge in design patterns - look at the 4 Amigos book!

>Q2: I just want to understand the theory behind Algorithms and Data Structure

You'll have to undertstand the O-notation at least and to be able to estimate the O-complexity of your algoriths. The Master theorem is not really needed though. You have at least to understand NP-complete complexity class (NP=P?). You'll have to be able to estimate run time of an algorithm - which algos would need thousands of years to complete?

Regards,
Marek

3. Summing Up

Hopefully some young programmer(s) will find it helpful!

For last 2 days - my book for $10 only!

There are a couple of days left for you all, if you want to get my book for $10 only!

In the course of the "Spring $10 Campaign" on packtpub.com you can purchase the eBook version of my "Hands-On High Performance Programming with Qt 5" book for $10 only until 30th of April.

So hurry on! here's the link: https://www.packtpub.com/application-development/hands-high-performance-programming-qt-5.

Get it when it's still fresh. It only came out this January!

PS: Sorry for the short notice, but somehow I overslept... Shame on me. 😞 Sorry.

A fairytale found on Stack Overflow

Somewhere on the Internets there is that little fairy tale about a little princess*, written in the
language of dreams, i.e. Javascript:

  function princess() {

      var adventures = [];

      function princeCharming() { /* ... */ }
  
      var unicorn = { /* ... */ },
          dragons = [ /* ... */ ],
          squirrel = "Hello!";

      return {
          story: function() {
              return adventures[adventures.length - 1];
          }
      };
  }

  var littleGirl = princess();
  littleGirl.story();

Can you read it? If not, there is this attempt of translation by Patrick M:

"...the princess() function is a complex scope containing private data. Outside the function, the private data can't be seen or accessed. The princess keeps the unicorns, dragons, adventures etc. in her imagination (private data) and the grown-ups can't see them for themselves. BUT the princess's imagination is captured in the closure for the story() function, which is the only interface the littleGirl instance exposes into the world of magic. – Patrick M Feb 28 '13 at 7:49"  

Still an alien language? Learn some Javascript closures, would you? And then a story unveils:

Domenichino [Public domain], via Wikimedia Commons

Once upon a time, there was a princess, her world was full of adventures: dragons, unicorns, talking squirrels (Narnia?). But because in this world she was only a little girl, she only could tell stories about her adventures. And nobody would believe her, because she couldn't take anybody into her magical land (due to a curse of an old, ugly witch called Ecma). So the princess was both happy and sad, because she couldn't share her adventures with anyone. An that's the tragic of sorcery, you have always to pay a price for it...

Now that you are in the know, did you notice, that the princess doesn't tell anyone about Prince Charming?

--
* source: https://stackoverflow.com/questions/111102/how-do-javascript-closures-work/6472397#6472397

Birthday paradox, Lotto and learning

Warning: this post is about how we learn but in reality we don't.

You may know the "birthday paradox" - it's a cute little story in probability theory, and as it happens it might be useful to know in a programming interview. So many of us learn about it and might even be able to derive the probability bound and to reason about it. But do we really learn? Or do we just memorize some story which will be called out in the "technical interview"?

Let us apply it to the case of lottery gambling. ...

The hard question here is - which numbers should I choose to win the jackpot. Well, the answer is, we don't know. The not so hard question is - which numbers NOT to choose. Here we can definitely offer some responses. We shouldn't choose the numbers most people would choose. Can you sense the application here? Well, most people will use their birthday date in some form (as it's the number they are most accustomed to). And the birthday paradox teaches us that... we ourselves shouldn't use it!

Would you see that? Possibly not. No party, no room, no people talking to each other as in the classic setting of the story. That's sad. That's not what I like about maths (and programming). But isn't it like that in the real life? If you'll be interviewed you have to reproduce the known answer first. If you're good at it, some deeper questions will follow, most of them with a known answer. And we learn that stuff to be used in an interview... But is that learning?


PS: admittedly, this isn't any direct application of the paradox, but rather a "reverse" one, nevertheless I see it as cool math giving hints in seemingly unrelated problem. And when we learn about it, we don't play enough with ideas, we just want to "pack it in" and have it ready for that interview.

Local language trends 2009

I just had a look on the statistics pages on our local IT freelancer website (http://www.freelancermap.de/) and found the results pretty interesting. First let's have a look at the languages which are most popular in the freelance projects. The picture below shows the languages, the supply of programmers (the blue bar) and the demand in projects (the red bar).

As it seems, here in Germany there are only two serious languages: C/C++ and Java. Well, ok, Visual Basic and C# are sough after rather strongly (red bars), but there seems to be too little supply. Is that the fear of a vendor lock-in or is it just because Microsoft is considered evil that the programmers don't like .NET? The same case of too little supply for PHP, but here I must mention that the hourly rates for PHP tend to be rather low - PHP still considered a hacker language?


And now look at the last but one language with a longwinded German name I won't retype here (too lazy). In fact it's not a language of its own, but rather denotes "all the other ones in there", which includes everything fancy (or just plain old). You see there is too much supply, the IT managers seem to be more conservative than programmers, no surprise here.

Which leaves us with C/C++ and Java. Java is unmistakeably the 500 pound gorilla here, but it's hopelessly over-supplied (blue bar)! For C/C++ the situation isn't so dramatic, and I'm glad I specialize in C++!

The proposed course of action here: go away from Java (or well, from everything else for that matter) and start on .NET!

Now the overview of technologies in the freelancer projects:

Software development comes first (still a little place for more work - red bar!), then system management (plus "service and support"), however the suply here is much too big (blue bar)! It's just as bad as for SAP programming - in the past the eternal cash cow with ridiculously high hourly wages, now it's a real "problem child" - the market seems to be breaking down. Banking crisis anyone? For Web development and "graphics, content and media" there's much too much demand, just like in the PHP case above. Then the ominous field of "IT consulting", where I don't have any idea what it is, sorry, no comments there :-/. One interesting field is "Executive consulting" with so much demand and so little supply, maybe everyone is just too shy to position theirself in that niche?

The proposed course of action here: either stay with software development or move into "Executive consulting"!

Having said that: Merry Christmas you all!

Songs in code

Won't explain what they are, because it's obvious. These two made me laugh:

Bob Marley's (and Groovy's):

  4.times{
  !woman == !cry
  }

and REM's (and SQL's):

  DROP TABLE MyReligion

but normally they are boring, uninspired or plainly wrong, like this one:

  while(young)
  {} // loops forever

Come on, the whole thing is that young is a volatile variable, which will somehow, sometimes be set to false! ;-)