Overview
This website consists of two parts:
- the C++ source code of my solutions to more than 300 Project Euler problems
- about ten PHP scripts to generate HTML code on-the-fly - solely based on the C++ source code !
This enables me to rapidly apply visual and structural changes to my website.
C++ compiler
GCC is my compiler of choice but almost all files can be compiled with Visual C++ or Clang, too.
I decided to settle with C++11 because it's widely supported and there are very few features of C++14/17 that justify switching to those newer standards.
(whenever the code requires C++11 then C++0x is usually fine, too, so GCC 4.7 should be sufficient)
Live Tests
My live-tests are a three-step procedure:
- filter user input and reject invalid parameters (done in PHP)
- forward valid input to STDIN, run the program and grab STDOUT (compiled binary)
- check whether output matches the default answer and suppress it, else return it wrapped in a JSON packet (in PHP)
Memory consumption is limited as well but I restrict the acceptable input in such cases so you won't notice it at all.
Markdown Syntax
When you look at the comments of my C++ files then you will notice a few strange symbols: that's Markdown syntax.
For example, a link is described as [my link text](http://myurl.com)
.
I heavily modified Johnny Broadway's Slimdown
class (see this gist at Github) to fit my needs - it's now more than twice as big.
The most important changes are automatic detection of mathematical formulas which will be rendered by KaTeX (see next chapter).
Properly Displayed Mathematical Formulas
The wonderful KaTeX Javascript library renders all formulas.
A bit of PHP processing allows me to use a slightly simplified syntax, e.g. remove the backslash in front of commonly used functions, such as sqrt
instead of \sqrt
.
I tried MathJax but it was much slower, not even mentioning its huge file size.
My optimized KaTeX distribution needs about 30 kB (minified and compressed) plus a few fonts which are about the size.
C++ Syntax Highlighting
My C++ syntax highlighting is far from perfect but surprisingly simple:
I "stole" quite a substantial amount of ideas from a posting on Dominic Szablewski's blog.
Now about ten regular expressions cover the vast majority of use cases and I can live with a few pitfalls every now and then.
Almost all other syntax highlighting libraries are much, much bigger and have their own shortcomings.
Virtual URLs
None of my website's URLs actually exists. There is no https://euler.stephan-brumme.com/inside/ - but there is lots of URL rewriting happening in the background
that finally executes inside.php
(which can't be accessed directly).
This gives me the power to easily control what parts are accessible and which are hidden.
For example, if I solve the most recent problem then I block access until a new problem is published by Project Euler.
And based on my logfile I know that this happens quite frequently ...
Even standard URLs like https://euler.stephan-brumme.com/1/ are rewritten inside the Apache server (mod_rewrite
) such that a PHP file is executed with parameter 1
so that 1.cpp
will be parsed.
Meta Data
My C++ lack a few things:
- difficulty (in percent)
- allowed input range (for live tests)
- the solution (needed to prevent my program from showing the correct solution right away)
Heatmap
Please click on a problem's number to open my solution to that problem:
green | solutions solve the original Project Euler problem and have a perfect score of 100% at Hackerrank, too | |
yellow | solutions score less than 100% at Hackerrank (but still solve the original problem easily) | |
gray | problems are already solved but I haven't published my solution yet | |
blue | solutions are relevant for Project Euler only: there wasn't a Hackerrank version of it (at the time I solved it) or it differed too much | |
orange | problems are solved but exceed the time limit of one minute or the memory limit of 256 MByte | |
red | problems are not solved yet but I wrote a simulation to approximate the result or verified at least the given example - usually I sketched a few ideas, too | |
black | problems are solved but access to the solution is blocked for a few days until the next problem is published | |
[new] | the flashing problem is the one I solved most recently |
I stopped working on Project Euler problems around the time they released 617.
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I scored 13526 points (out of 15700 possible points, top rank was 17 out of ≈60000 in August 2017) at Hackerrank's Project Euler+.
My username at Project Euler is stephanbrumme while it's stbrumme at Hackerrank.
Look at my progress and performance pages to get more details.