Overview
Usually I try to solve the original challenge from Project Euler first and then tackle its modified version at Hackerrank which is often harder.
I'm a software developer and don't have the mathematical knowledge to solve most of the hard problems.
However, I'm quite good when the solution "just" requires a smart choice of data structures and/or clever use of raw CPU power.
If you look at my overview then you'll see that I never solved a problem with a rating of more than 70%.
And with about 300 solved problems I'm hitting a wall: no easy problems are left and most of the unsolved problems just don't interest me.
That's why I stopped after I submitted my solution to problem 577: 310 out of 617 problems solved between February 22 and December 31, 2017.
It has been fun - but now spend my time on other projects, such as create.stephan-brumme.com.
My favorite problems are those with a Dynamic Programming solution.
And of course these little gems that can be somehow applied to real-life computer problems:
Some code snippets are part of several problems and I added them to my toolbox.
Update December 2019: the code is part of my GitHub repository, too.
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.
Most recently solved
December 31, 2017: Problem 577 – Counting hexagonsDecember 27, 2017: Problem 279 – Triangles with integral sides and an integral angle
December 20, 2017: Problem 324 – Building a tower
December 18, 2017: Problem 458 – Permutations of Project
December 12, 2017: Problem 310 – Nim Square
December 11, 2017: Problem 308 – An amazing Prime-generating Automaton
December 10, 2017: Problem 565 – Divisibility of sum of divisors
December 8, 2017: Problem 485 – Maximum number of divisors
December 6, 2017: Problem 375 – Minimum of subsequences
December 4, 2017: Problem 615 – The millionth number with at least one million prime factors
... and 300 more ...