Coding challenges

These great challenges are published at https://codingchallenges.fyi by John Cricket Twitter

Checkout the newsletter also here on https://codingchallenges.fyi/

I have started on week 1 in implementing the challenges starting March 2023. Since then John published every week a new challenge.

I love the most the real world applications as Redis, load balancer, webserver, IRC client, json parse, url shortener and more to come ....

I started to use Discort and Twitter and https://github.com/CodingChallegesFYI/SharedSolutions to share my solutions.

I decided to implement it back with Java. I have been working with Java since v1.0 back in 2000 and worked with it professionally for more than 18 years. Then I started with C# and powershell working with Azure Cloud.

Write your own

Here you can find all my implementation, challenge see: https://codingchallenges.fyi

See also other solutions implemented: https://github.com/CodingChallegesFYI/SharedSolutions

Some feedback and and my personal complexity rating

1 * = simple, 5 ***** = a real challenge

no	Build Your Own	Link code	Description	Complexity
1	wc tool	no-1	very simple tool to get back with Java tooling, pipelines and arg parsing	1 *
2	JSON parser	no-2	this is a great project to implement scanner and parser tried to strong test it with lots of test cases (pos and neg cases)	2 **
3	Compression tool	no-3	get into the Huffman Encoder/Decoder quite complex binary trees with insertion logic without testcases - no chance to solve this riddle awesome experience John	2 **
4	cut Tool	no-4	little linux tool. simple and easy	1 *
5	Load Balancer	no-5	invested quite a bit of time for fully dynamic and reliable Round Robin and chaos engineering tests to kill processes	2 **
6	sort Tool
7	Calculator
8	Redis Server	no-8	this is by far the best challenge I have every implemented learning the redis protocol step by step I extended the challenge with lots of commands	3 ***
			this is AWESOME idea by John to implement with this you can really learn a new language I implemented a lot of test cases: I used chatGPT to generate test cases
9	grep Tool	no-9	I used just my mobile phone and javascript to implement it had some headache topics with * and folders .... check it out	1 *
10	uniq Tool
11	WebServer	no-11	cool to learn the HTTP1.1 protocol and implement it without support libraries I extended my work to implement Servlet types (static files, rest) with routing	2 **
12	UrlShortener
13	diff Tool
14	shell
15	cat Tool
16	IRC Client	no-16	great to learn the protocol of IRC massive refactoring from step 2 to step 3 - as supposed I tried to this not to build a scanner but use regexp for the different patterns. finally I must say - I like scanners. without https://regex101.com/ - no chance to implement this type of regexp	2 **
17	memcached server	no-17	fully functional server with many commands, memory mgmt cmd pattern to plugin more if interested lots of testcases additional memcache client test implement a server and a client Later: try to use consistent hashing for multiple servers	3 ***
18	spotify client
19	discort bot	no-19	configured my own discort server implemented a pluggable cmds not deloyed on a server	1 *
20	LinkedIn carousel
21	sed-tool
22	DNS resolver	no-22	implemented A, cname, mx, txt records resolver does same printout as 'nslookup' can be parametrized to test dns principles default using localhost loopback 127.0.0.53:53	3 ***
23	traceroue
24	realtime chat client and server
25	NATS server	no-25	implemented NATS server and client cool challenge	3 ***
26	git client
27	rate limiter
28	ntp client
29	scheduling automation app
30	Lisp interpreter	no-30	implemented full Lisp tokenizer, parser and interpreter implemented > 30 built-ins incl pure function caching for faster execution	4 ****
			love Lisp. used it to build first neuronal network with 10 own perceptron (back in 1994) additional idea: build interpreter to build this again
31	QR Code Generator	no-31	implemented full spectrum of codes: alpha, byte, kanji with all versions support, quality impl debug support with text canvas	5 ******
			impl regions algorithm of rectangles to impl positioning of bits automatic masking tutorial awesome but some missing tips complexity totally underestimated. testcases are key
32	Crontab
33	head
34	jq	no-34	used my json parser from no-2 implemented own parser for jq expressions own json serializer for pretty printing new jq evaluator of the expressions	2 **
35	Google Keep

A brief history of my coding languages learned and used

Year	Language	Notes
85	BASIC, Assembler	Back in 1985 I learned to code in BASIC on Sharp 1401 and with MS-DOS in 1985 on my 1st PC 4.77 Mhz, with a Hercules monochrome grafic card, <br/1MB RAM, 20MB Disk :-) and Floppies. And sure got to know Assembly to do all crazy stuff down the low level.
87	Pascal	With the Apple Macintosh 512e used in highschool I started coding with Pascal by Niklaus Wirth. During an internship I used Pascal to run on an VAX by DEC
89	Modula-2	Modula-2 as the successor of Pascal also by Niklaus Wirth and here I started all my private coding
90	bash	with the usage of UNIX systems at ETHZ I started with scripting
90	C and C++	with the first university challenges I touched C and C++ but did not like it.
91	Oberon, Oberon-2, XOberon	At University ETH Zurich I used to code in Oberon by Niklaus Wirth and Oberon-2 the object oriented extension of Oberon and XOberon at Institute of Robotics. I loved it.
93	Lisp + Prolog	Beside Oberon we use to code our first Neuronal network with 10 neurons in Lisp and our first knowledge base in Prolog - something completly different but nice.
94	Smalltalk	At my first business job in 1994 I learned and loved Smalltalk - the real object oriented language. In a private project, I even implemented my own Smalltalk parser, compiler and byte code runtime environment in Oberon based on the architecture and bytecode from A little Smalltalk. I also used Visual-Age Smalltalk in my STA in Dallas, TX, USA in 1999.
2000	Java	In 2000 I arrived at the WWW finally and I learned Java and JDK 1.x and used Java for more then 18 years in business and private.
2011	Javascript, NodeJs	During Hackathons I learned to code in Javascript, node.js, Solidy
2014	Objective-C, Swift, Swift-UI	with winning an innovation award in 2014 I started coding with Apple Objective-c for iPhone and Apple Watch Series 1 and later with Swift and SwiftUI for our winning Hackathon idea m-clippy.
2020	C#	Coding for my beloved Hololens 1 developer edition I started with Unity and C#. Including Hackathons at Microsoft in Redmond with Principal engineers from the Hololens team. Implement 1st holographic bot called LoloBot.
2021	Powershell	Then I arrived in the Azure Cloud and used C# and powershell for more than 3 years now.
2023	Typescript	Now back at OpenAPIs development with Nodejs (nestjs) with typescript
2023	Back in Java	Now for the Coding challenges I flipped back to Java. Unfortunatly Oberon and Smalltalk are almost dead.

*** and maybe I forgot many languages I learned beside: German, French and English.

Thank you

I wanted to thank John Cricket for these challenges and I encourage every Engineer from Junior to Principal to do this. Learn a new language or get back to language you have used to code (as me here in Java).

And also learn to understand real-world applications while writing your own version of it.

thx Lolo

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