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Project Euler

projecteuler.net

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Re: Project Euler

#121

Post by iClaudiusX »

archgoon wrote: post #79

http://rosalind.info (named after Rosalind Franklin) is similar, for bioinformatics. It has the advantage over Project Euler that it provides some background and hints to the solution to the problem it presents, plus an additional graph structure of concept dependencies. Many of the bioinformatics problems are also pure Math and CS, so it's probably of broad interest beyond just an interest in biology.

Rosalind is a great intro to the fundamentals like graph and set theories, efficient string algorithms, combinatorics, etc.

My one criticism is that the examples for some problems are trivial and don't adequately account for any of the complexity of the problem. It can feel a bit like the "Learn to Drawn an Owl" meme: Step 1) Draw an oval. Step 2) Draw the rest of the owl.

Re: Project Euler

#123

Post by ronnypostsstuff »

utopcell wrote: post #68

Are there any 200+ PE readers here ? If so, how long did it take you to reach you level and what was the most challenging problem you solved ?

164 here. I did it on and off for many many years. Personally I don't think there is much value in grinding these. It's rather a fun pastime every now and then.

That said, I believe the 100-150 easiest (i.e. solved by the most people) problems are all OK. Many of them take one hour or less. I think, it never took more than a weekend for one.

Many of the ~2006 problems can be brute forced nowadays with a low level language, which makes them quite a bit easier.

Re: Project Euler

#124

Post by debbiedowner »

To ask people who solved many of these questions:

Once you find "the" trick, is there still a lot of computation involved? Do you still write loops? How many orders of magnitude times do those loops run? How do you know when your code is too computationally intensive and you haven't found "the" trick yet?

Re: Project Euler

#125

Post by jimbokun »

gordaco wrote: post #75
nhebb wrote: post #52

Earlier quoted context omitted.

I came up with it too when I was in school. I was bored and staring at some tiles and noticed that for a square block of tiles with side = n, n^2 = sum(1...n) - sum(1...n-1). The funny thing is that, since then, I've looked at that formula several times and can't for the life of me figure out I got from the above formula to the the sum of the range formula. I guess younger me was smarter than current me.

You can arrive to the formula n^2 = sum(1..n) + sum(1..n-1) visually, separating a square into two triangles and fill them adding diagonals. Ok, that doesn't sound very informative, so let me show you an example. Let's start with a 4x4 square: OOOO OOOO OOOO OOOO Divide it into two triangles: OOOO OOO O OO OO O OOO Note that one of the triangles has a side of (n-1) and other has a side of n. Now, let's see how many e…

That is an outstanding explanation of the intuition behind that formula, and in ASCII no less! :)

Re: Project Euler

#126

Post by ronnypostsstuff »

Did any of you interview and having a good Project Euler account was positively recognized?

This never happened to me. No one seems to know the site. They seem to be mostly interested in Top Coder and similar platforms.

Re: Project Euler

#127

Post by enedil »

debbiedowner wrote: post #124

To ask people who solved many of these questions: Once you find "the" trick, is there still a lot of computation involved? Do you still write loops? How many orders of magnitude times do those loops run? How do you know when your code is too computationally intensive and you haven't found "the" trick yet?

If you write it and it doesn't finish in a minute, I'm sure it's not that trick.

Re: Project Euler

#129

Post by huherto »

Back in the day I solved the first ~100 problems in order. It was a great practice to sharpen your programming logic and I learned a ton of math. The problems became harder. But I haven't done any in many years. Do you think the newer problems are very very hard ? I have to admire the dedication of those who have kept on it.
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