## Search found 150 matches

Thu Jan 21, 2021 6:24 am
Forum: Discrete Mathematics
Topic: Counting constrained squarefree numbers
Replies: 4
Views: 2002

### Re: Counting constrained squarefree numbers

The same idea works for this case too. If I'm not wrong, you only have to learn to use the idea from Problem 1 (View Problem).
Sat Jan 02, 2021 11:36 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 740
Replies: 7
Views: 1120

### Re: Problem 740

It takes a simple brute force to verify that the intended process is 112233. The source of confusion is maybe because of the following words: “As before each person takes a random slip from the hat that does not contain their name. Then they do the same process again so that they end up with two sli...
Sun Dec 27, 2020 2:00 pm
Forum: Discrete Mathematics
Topic: How to compute a two-variable recurrence function C(n,n) in O(n) time?
Replies: 2
Views: 625

### Re: How to compute a two-variable recurrence function C(n,n) in O(n) time?

A simple idea is to convert them into bivariate generating functions.. For example, define

$\displaystyle F(x, y) = \sum_{n,k \geq 0}C(n,k)x^ny^k$

Use the recurrence you have quoted to arrive at an expression for $F(x,y)$. That should hopefully give you the required $O(n)$ algo.
Wed Dec 09, 2020 4:15 pm
Forum: Clarifications on Project Euler Problems
Topic: Problem 737
Replies: 2
Views: 1409

### Re: Problem 737

It's very early to post values hacatu. Please keep working on the problem and remove the values. Possibly, someone will reply and you can get the chat in a private forum.
Tue Nov 03, 2020 6:35 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 727
Replies: 2
Views: 714

### Re: Problem 727

Hi yourmaths, "chosen uniformly" here means we choose one triple from among those which satisfy the limits AND the GCD condition. If you consider only the limit, you'll have a total of $\displaystyle \binom{100}{3}$ triples to choose from. But we will have lower number of triples because o...
Tue Apr 28, 2020 3:28 pm
Forum: News, Suggestions, and FAQ
Topic: Removing incentive for spoilers
Replies: 13
Views: 6134

### Re: Removing incentive for spoilers

Hi vamsikal3, It's been a while we had a chat. Hope you are doing good.. Regarding the discussion here, I think you've put it nicely here. ... So, if unlocking problems that I cannot solve after spending a few days on it helps me learn/understand new mathematics or programming techniques. I believe ...
Mon Apr 27, 2020 9:22 am
Forum: News, Suggestions, and FAQ
Topic: Suggestion - save to clipboard when posting?
Replies: 10
Views: 4465

### Re: Suggestion - save to clipboard when posting?

Great feature euler. Came in handy today.. A big thanks!!
Fri Apr 17, 2020 6:58 pm
Forum: Programming languages
Topic: Any Mathematica tricks to share?
Replies: 2
Views: 1967

### Re: Any Mathematica tricks to share?

The undocumented Algebra`MatrixPowerMod. Useful in many PE problems.
Sun Feb 16, 2020 8:47 am
Forum: News, Suggestions, and FAQ
Topic: easier new problems?
Replies: 4
Views: 2648

### Re: easier new problems?

This post has a lot people sharing their experience at your (or our) stage.

I've also listed some topics in the above thread which can help in solving many PE problems.

Happy Solving!!
Sun Aug 25, 2019 7:34 pm
Forum: News, Suggestions, and FAQ
Topic: Username not known
Replies: 9
Views: 3297

### Username not known

Hi, For some reason, I can't login to my account. PE says 'Username not known'.

Can anyone let me know why this is happening?
Wed Aug 21, 2019 3:55 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 613
Replies: 9
Views: 5504

### Re: Problem 613

It's just a mathematical description RishadanPort. To make it more abstract, if you randomly select a point inside a right angled triangle and randomly choose some direction to draw a line (starting from the point we chose), what is the probability that the line intersects the hypotenuse?
Fri Jun 28, 2019 6:15 am
Forum: News, Suggestions, and FAQ
Topic: Errors/Warnings/Bugs
Replies: 628
Views: 220904

### Re: Errors/Warnings/Bugs

We cannot make two consecutive posts in the same solution forum. I think you should be able to edit your post and add the content in the same post.
Mon May 27, 2019 11:33 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 671
Replies: 3
Views: 4904

### Re: Problem 671

671 Hi All, Tiling which are identical after rotating the loop about its axis considered different? Only if I consider them different, I get F_4(3) = 104. Else am stuck at 92. I'm not sure whether 'reflecting horizontally or vertically would give a different tiling, these tilings are to be counted ...
Mon May 06, 2019 9:17 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 272
Replies: 15
Views: 12358

### Re: Problem 272

Hi mdean,
If you could PM your value, I can confirm it.
Tue Mar 05, 2019 4:43 pm
Forum: News, Suggestions, and FAQ
Topic: Project Euler Style Sheet Update
Replies: 33
Views: 18288

### Re: Project Euler Style Sheet Update

The kudos count is aligned properly now. Kudos for that euler...
Mon Mar 04, 2019 12:59 am
Forum: News, Suggestions, and FAQ
Topic: Project Euler Style Sheet Update
Replies: 33
Views: 18288

### Re: Project Euler Style Sheet Update

Many thanks to the PE team for the new style. The site looks great with the new styling.

The only issue that I saw was as that of MHealy. For non-permananent posts, the kudos are slightly mis-aligned in Chrome.

Truly appreciate the hard work in getting PE a new style.
Tue Nov 27, 2018 10:29 am
Forum: News, Suggestions, and FAQ
Topic: Errors/Warnings/Bugs
Replies: 628
Views: 220904

### Re: Errors/Warnings/Bugs

For me the problem appears in Chrome but not in IE...
Tue Nov 27, 2018 4:42 am
Forum: News, Suggestions, and FAQ
Topic: Errors/Warnings/Bugs
Replies: 628
Views: 220904

### Re: Errors/Warnings/Bugs

Now I have this problem...

If I try to view my posts from 173-180, then am directed to the sign-in page even though am not signed-out of PE.
Fri Aug 24, 2018 5:14 am
Forum: Programming languages
Topic: which compiler to use for c++ programs
Replies: 2
Views: 7299

### Re: which compiler to use for c++ programs

Like v6ph1 said, if you are looking for online compilers, repl is my favourite..
Fri Aug 10, 2018 6:52 am
Forum: Number Theory
Topic: An Infinite Prime Number Generator
Replies: 5
Views: 9636

### Re: An Infinite Prime Number Generator

I changed the code to remove the loop-checking and use modified-step values but still no improvements in timing. For example, the mod-2 version takes ~ 75 secs to list all primes upto 10^8, the mod-6 version takes ~ 85 secs whereas the step-adjusted-mod-6 version takes ~ 95 secs. step-adjusted-mod-6...