This is excellent, really happy to hear you had fun rewriting it. Really like the functional approach of solving this challenge. I didn't even know you could write functions within functions like this...

Thanks for the feedback

Great to hear the positive feedback Martin, next vid next week.

Thanks Andrey.

Excellent, much more to come this friday.

You're very welcome Andrea, I'll bring you another present next year.

Hopefully this algorithm wasn't too difficult to follow. It's a pretty common problem set CS students go over and often a similar version of this problem is given during interviews. Hope you had fun with it Roger.

Hi Robert, yeah I would like to get my hands on more complicated examples of trees. I've been out of college for quite some time and need to do some research on theory again.

Haha same here man, its amazing how easy it is for your memory to slip especially when your not actively writing these algorithms on a daily basis. Like I say, I think your implementation, which essentially *traverses* the tree, is perfectly adequate for production use as long as the algorithm that parses the raw expressions and tokens to *produce* the actual AST being traversed takes into account the order of operations. This is what I'm attempting to do at present for a project I'm working on; I need to be able to take a bunch of arbitrary arithmetic expressions and parse and order them (according to BODMAS) to produce a tree; once I've done that then an algorithm not to dissimilar to the one you present here may be used to traverse and process the resulting tree. Anyway, great video!!

Excellent, AST is a very exciting problem set that allows you to understand recursion on another level.

I need to get my hands on that book to get a better idea on what kind of useful algorithms are covered. I feel like Swift is a very new language and I would like to cover more relevant iOS type of challenges.

Yea its pretty good it covers some of the basic algorithms(and some really hard ones), but I am not sure what kind you may have ran into during interviews. Its really hard for me to study for them because you may run into any type of problem, so I have to be good at all the datastructures. But your vids are helping alot!!

This example was just about evaluating the tree, not making it. Making an AST is even more difficult. To put it simply you need to know a little about Finite Automata(kzfaq.info/get/bejne/iNB_drWKyc2cco0.html) and Compiler Design. There are many algorithms to create an AST Tree, most popular is Recursive Descent Parsing(kzfaq.info/get/bejne/m7ynn5OZ0K-WYY0.html). In the Recursive Descent Algorithm, you can specify rules for operations. These are the basics in Compiling code and Programming language design.

Crashlytics

Well, what kind of data structures/algorithms would you like to see?

well, i dont kow how to put this, like data structure inplementaion on App such Firebase chat where user can update their details on app like name, email address, or profile image from seetings.

Can you tell me your implementation of the calendar? I'm curious what you've attempted.

Lets Build That App 🙄 I just implement calendar with fscalendar... But it have some issues with almofire... it shows 4error . But so far I can run the app with this red error...But I don't know if it will course any issues when I pull to app store..So I planing to have my own calender... But no idea where to start..If u pull the starting idea I will be great..or eg twice a week we all together can create custom class file for such things like discussion session.

This is Swift, a language that is meant to replace Objective C for iOS development. Java will never be obsolete in the corporate world.

I'll second that!!! Been programming for as long as I can remember (circa 18 years). As you can imagine I have written code in numerous languages in that time from low-level Assembly to high-level Visual Basic and I'm yet to come across a language that has the shear expressiveness,flexibility and power of Java. The fact that I can write a piece of logic ONCE and deploy it as part of a Windows/Mac Desktop App, A Web Server App, Android Tablet or Mobile Phone App WITHOUT any platform-specific recompilation perfectly illustrates this point. Its not so much the Java language (and associated syntax and semantics) that was a breakthrough all those years ago, but rather the Language Runtime Paradigm that underpins it. The idea that perhaps, if virtualised, the entire runtime could be ported to different platforms thereby abstracting away and negating the need for developers to target said platforms themselves; developers can essentially write platform agnostic code.

还行还行 今天的影片说实话不容易录

It's not easy, but we have faith in you! 👊

谢谢 I think I will go over an easier algorithm next Friday.

+Jonathan Green yeah it's unfortunate that developers are tested on unrelated algorithms during interviews that don't really gauge their competence in building complete projects. I think you did the right thing.

@Jonathan Green Still, learning a little Data Structures and Algorithm theory can't hurt can it? Personally speaking, I have always been fascinated with the topic (Data Structures and Algorithms) and remember thoroughly enjoying learning how to store and perform operations on data in the most efficient manner possible. Plus there *are* certain computer science specific algorithms and techniques that are vital to any application development, Recursion being principal among them. I use recursion in my day-to-day programming almost as much as iteration!! An incredibly common recursion use case my be where your App creates a number of nested folders and there is a requirement to delete the root folder and all nested folders contained within it.

Better this than some math brain teaser algo under time pressure.