[HN Gopher] Project Euler
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Project Euler
Author : swatson741
Score : 242 points
Date : 2025-11-12 17:24 UTC (5 hours ago)
(HTM) web link (projecteuler.net)
(TXT) w3m dump (projecteuler.net)
| thornewolf wrote:
| I have done Project Euler very sporadically since high school. To
| date I've only done problems 1-54. Despite this, I think the
| website was a big contributor to my love of programming. I found
| it before knowing about leetcode and I think it prepared me well.
| I think I owe Project Euler a decent %-age of my eventual entry
| into Software Engineering as a field.
| ljlolel wrote:
| Ditto!
|
| Also a great way to learn a new programming language is to try
| project Euler problems with it.
| Gormisdomai wrote:
| This website was a part of my education as a computer scientist
| and seeing it here again I'm curious for the full story of how
| this site was made. Who made it, what do they do now, is it part
| of a broader project they have?
|
| There is only very basic info here:
| https://en.wikipedia.org/wiki/Project_Euler
| observationist wrote:
| https://archive.is/iEQxy
|
| This article is excellent. It mentions the creator, Colin
| Hughes, and the story behind the project, but it boils down to
| a passion project for him.
| campbel wrote:
| Back in early 2000s, before hackerrank and similar coding
| sites, this is what my professors recommended for training
| programming skills.
| Sparkle-san wrote:
| Like many others here, Project Euler was foundational in my
| education and growth as a programmer.
|
| Leonhard Euler himself is an incredible figure and arguably the
| most prodigious contributor to mathematics throughout history. So
| much so that people started naming things discovered by him after
| the next person to have proved them.
|
| https://en.wikipedia.org/wiki/List_of_topics_named_after_Leo...
| graycat wrote:
| Glanced at the exercises. It appears that two of them have
| numbers arranged in a triangle and ask for a longest path.
|
| Hmm. Given such a triangle, let m be the largest number in the
| triangle. For each x in the triangle, replace it with m - x. For
| the resulting triangle, solve it to give the shortest path using
| one of the well known network shortest path algorithms.
| thaumasiotes wrote:
| > Hmm. Given such a triangle, let m be the largest number in
| the triangle. For each x in the triangle, replace it with m -
| x.
|
| By the time you've actually done these two steps, you could
| have finished the problem with a dynamic programming approach.
|
| (Starting from the bottom row and working upward, replace each
| cell in the row with the length of the longest path from itself
| to the bottom, which you can know by checking which of its two
| children has the longer path associated.)
| bre1010 wrote:
| I discovered project euler as a novice programmer in high school
| around 15 years ago. I loved how solving a problem unlocks a
| secret forum only available to other solvers. I would spend hours
| reading through everyone's prior solutions and trying to
| understand them. One guy had tagged his profile as "haskell" but
| would always provide his solutions in ruby which threw child-me
| for quite a loop (I actually thought ruby and haskell were the
| same language for some time)!
| zkmon wrote:
| A great one of my favorite websites of the past. Wonder how they
| are coping with the issue of their users using AI to solve
| problems.
| Schiphol wrote:
| I suppose I wonder how those users are coping with having the
| robots do all the stuff instead of them doing some of the
| stuff.
| unkulunkulu wrote:
| The most fun on this site is solving a problem and then having
| your mind blown by solutions in Apl/j/k and trying to guess what
| they mean without knowing anything about those languages
| omegaham wrote:
| See also Uiua, a newcomer to the "extremely cool but completely
| incomprehensible language" family!
| taeric wrote:
| Even better than the crazy languages, is seeing some
| fundamental math used to prevent having to do a ridiculously
| expensive search.
|
| That said, raw brute force often did far better than you'd like
| to admit.
| debatem1 wrote:
| The biggest thing I learned from PE was that neither elegant
| theory nor brute force had a monopoly on successful
| optimization strategies. It's been something I've carried
| with me ever since and has over and over again proven its
| value.
|
| A real gem of a resource.
| matthewaveryusa wrote:
| I attribute project euler for instilling the playful enjoyment of
| writing programs in college while I was studying electrical and
| computer engineering. I owe my career to it!
| 0x1ch wrote:
| I remember visiting Project Euler back in 2013/14 or so. Was
| really my first introduction to programming exercises as youngin.
| Probably did fifteen or so of them before ADHD kicked in though.
| A small gem on the web.
| codexb wrote:
| Wow, I can't believe this is still around! I'm glad to see
| artifacts from the past like this are still out there on the
| internet.
|
| Makes me miss Google CodeJam though.
| ketanmaheshwari wrote:
| I solved a few using AWK, fun:
| https://github.com/ketancmaheshwari/projecteuler
| nik9000 wrote:
| I ranked on that once! I was like the 23rd person to do one of
| the new problems one time. Just about as low as you can rank. It
| was a fun puzzle but you had to be awake at a funky time to do
| it.
| sizzzzlerz wrote:
| i was a euler fanatic some years ago reaching problems in the
| 500s albeit, skipping problems along the way. at that point, too
| many problems required a deeper math background than i possessed
| so i abandoned it. what amazed me was that others composed
| solutions that solved problems in mere milliseconds that brute
| force approaches would still be running when the universe cooled
| to absolute zero.
| rbongers wrote:
| I only reached the 100s back in the day. What amazed me was
| that it seemed like every problem had a paper solution, when it
| would take any computer algorithm thousands or millions of
| computations to solve the same problem.
| rufus_foreman wrote:
| I played around with some of the easier problems, my favorite
| was a couple times when starting with the obvious brute force
| solution in code and then refactoring and simplifying it
| iteratively ended up getting me the paper solution.
| theoldgreybeard wrote:
| I love running euler problems when trying to learn the basics of
| a new programming language. I have a small collection of programs
| in like 10 different languages that I keep around as a reference
| for things because I always try to use language-specific features
| to solve the problems, and then I reference them as examples.
| gregdeon wrote:
| Wow. You reminded me of a computer engineering class years ago
| where we wrote assemblers and emulators for a simple
| architecture. I tested mine by writing a solution for one of
| the first Project Euler questions!
| callc wrote:
| I too owe had my love for programming captured through project
| Euler. I am immensely grateful to my maths prof who introduced me
| to it.
|
| I also love looking back at my old PE code and having absolutely
| no idea what it doing. No comments, no docs, no notes. From a
| different era.
| sbmthakur wrote:
| Hackerrank also used to host(still has?) PE problems with
| additional test cases.
| nurettin wrote:
| 2007 I remember writing one-liner ruby solutions up to 100.
| Imnimo wrote:
| These are both a lot more fun, and a lot more educational than
| leetcode problems. Strongly recommend for anyone looking for
| practice problems when learning a new language or whatever.
| BeetleB wrote:
| Ha! I did a lot of these around 2007-2008. I solved the first 100
| or so ones. Solving these were more fun than any other
| programming problems site I've seen. I quit it when I realized I
| was spending 4+ hours per problem - I couldn't justify the time.
|
| Beyond a certain point, most required some knowledge of
| elementary number theory.
| coef2 wrote:
| I agree with you. About a decade ago, I got really tired of
| coding interview prep. I somehow ended up getting into Project
| Euler and worked through the first 100 problems. It was a great
| way to learn a bit of number theory and regain my interest in
| programming.
| goalieca wrote:
| Same timeline for me! This was my great procrastination side
| quest during grad school. I learned haskell and a bit of ocaml
| working on these. Functional languages are extremely well
| suited to these kinds of problems.
| pkoird wrote:
| I remember it vaguely but there used to be a badge awarded for
| being among the first 100 people to solve the problem. I was
| obsessed with getting that badge to the point that I spent
| obscene amount of time solving the-then recently released problem
| even when the following day was my final exams. I did manage to
| get that badge though. This was circa 2013. Fun times!
| anthk wrote:
| Thanks for reminding me this; I'd try to solve them both in
| Scheme (s9fes) and JimTCL.
| shaunxcode wrote:
| this is how you end up getting into APL/array langs for sure.
| meken wrote:
| One of my best memories was in undergrad there was one semester
| in 2013 where half a dozen of my CS classmates and I competed to
| try and solve the most Project Euler problems. We had a
| leaderboard and everything.
|
| I saw first hand how much faster my friend's Java solutions were
| than my Python solutions.
|
| Good times.
| aiahs wrote:
| I did a lot of these when I was around 15-16 and it solidified
| for me my interest in CS but in general abstract thinking and
| problem solving. Great site.
| darylteo wrote:
| How I learnt about prime number sieves.
|
| Good prep for Advent of Code in 2 weeks.
| davidhariri wrote:
| I learned so much from this site- including that so much
| education comes from being prompted to ask the right questions.
| peterkagey wrote:
| I wrote Problem 619 (https://projecteuler.net/problem=619) which
| was published on 2018-01-27 and solved by 474.
|
| The problem was based on 2013 Putnam Exam problem A2
| (https://kskedlaya.org/putnam-archive/2013.pdf) which I took at
| the end of undergrad.
|
| I got an email six years later (in November 2024) telling me they
| accepted the problem:
|
| Greetings!
|
| Please excuse the email. It's quite possible that you are no
| longer active at Project Euler, but we are currently trying to
| retrospectively acknowledge contributors of problems.
|
| You were identified as being involved with Square subsets [619 m]
| in Sep-17.
|
| If you would like to be added as a verified contributor, please
| reply to this email and provide the username you currently use at
| projecteuler.net. Please note that contributor usernames will not
| appear publicly, rather they will be used internally to unlock
| new contributor awards we are introducing.
|
| Regards,
|
| Project Euler Team
| webo wrote:
| I was curious if LLMs are good for this problem.
| ChatGPT-5.1-Thinking one-shotted a correct Python script
| without any library use (https://pastecode.io/s/jg6ggxpm).
|
| Claude Opus failed to solve after trying for a while.
| kekqqq wrote:
| No one tells you that they delete inactive accounts. I used to
| have over 300 solved problems htere. Now it is all gone, all the
| effort, but the skill remained of course.
| inasio wrote:
| A few years back (10 maybe?) they had a disk crash, and there
| was a notice that for people with 100 or more problems solved
| they'd do an extra effort to recover their solutions and add
| you back, not sure if it was only posted on the main website. I
| was lucky to get my account back at the time
| yogsototh wrote:
| I remember there were data loss, but my account appears to have
| been recovered. You may try to login again, and with luck, like
| me you will get back your history.
| doodpants wrote:
| So, I gather that you treated your solutions as throw-away
| code, rather than keeping them? Kind of surprising, considering
| that some problems build off of each other, or otherwise
| benefit from sharing code; you never know when the code for one
| solution could be useful later. For example, a prime number
| generator/tester is necessary for many of the problems.
|
| (I have all my solution code, in source control no less, so if
| I ever lost my account, I could just run them all and re-enter
| the solutions.)
| medbar wrote:
| very surprised this project is still releasing problems weekly -
| I remember this being up when I was in high school. maybe I'll
| pick it up again since I only did the first ~30 or so back then.
| philiplu wrote:
| Not only are they still releasing problems weekly, they have a
| long backlog of problems waiting for release. I submitted a
| problem back in April 2024, and it didn't get published until
| October 2025 (problem 963). There's an excellent core
| development team that works with problem-submitters to get
| problems tuned up for Project Euler.
| senderista wrote:
| So much more fun than leetcode. OTOH, unlikely to help you in an
| interview.
| akudha wrote:
| Are there other similar sites? I remember this one, for
| bioinformatics
|
| https://rosalind.info/problems/list-view/
| phil-pickering wrote:
| I think a hat-tip is due to freeCodeCamp for introducing Project
| Euler (along with Rosetta Code) to a new generation of
| programmers:
|
| https://www.freecodecamp.org/learn/project-euler/#project-eu...
| SethTro wrote:
| I wrote Problem 371, https://projecteuler.net/problem=371 , as a
| high school student in 2012!
|
| I'm so happy to have spent twenty years of my life learning math
| and solving problems on Project Euler and elsewhere.
| fortranfiend wrote:
| _fake frustration_ yet another thing named after euler.
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