Search found 18 matches

by Eventhorizon
Tue Mar 06, 2018 4:52 pm
Forum: Combinatorics
Topic: BBC Article - Lego arrangements
Replies: 1
Views: 237

BBC Article - Lego arrangements

I read this morning a story about Lego on the BBC news app. It contained the following nugget: 915,103,765 - the number of ways to combine six two-by-four Lego bricks of the same color That seemed surprisingly high a number to me. Assume the following: the bricks are indistinguishable (all the same ...
by Eventhorizon
Fri Nov 17, 2017 1:59 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 613
Replies: 7
Views: 1813

Re: Problem 613

Thanks v6ph1 and LilStlker,

Finally got back to the problem and knocked it out in 10 minutes or so!
by Eventhorizon
Sun Nov 05, 2017 5:42 pm
Forum: Clarifications on Project Euler Problems
Topic: Problem 613
Replies: 7
Views: 1813

Problem 613

Not sure this matters, since it only applies to two points on the perimeter of the triangle, but what happens if the ant lands on the intersection of the hypotenuse and either of the short sides? There is a range of directions that involve the ant exiting the triangle crossing both the hypotenuse an...
by Eventhorizon
Thu Sep 14, 2017 1:38 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 146
Replies: 18
Views: 5132

Re: Problem 146

hk,

Thanks for your reply - only just saw it!
by Eventhorizon
Sun Aug 27, 2017 5:39 pm
Forum: Clarifications on Project Euler Problems
Topic: Problem 146
Replies: 18
Views: 5132

Re: Problem 146

Curious about this and similar problems: Regarding the one-minute rule, do you generate the primes you need in your code and thus include the time to generate the primes in the one-minute, or do you use a pre-populated list of primes? It takes my machine and R and what I think is a fairly good imple...
by Eventhorizon
Mon Jun 26, 2017 12:10 am
Forum: News, Suggestions, and FAQ
Topic: Suggestion: Searching Problems
Replies: 4
Views: 836

Re: Suggestion: Searching Problems

Jaap and hk,

Thanks for responding. Since I always log in it never occurred to me that Google would be able to crawl all the problems anyway.

I guess I should say "doh!".
by Eventhorizon
Sat Jun 24, 2017 6:22 pm
Forum: News, Suggestions, and FAQ
Topic: Suggestion: Searching Problems
Replies: 4
Views: 836

Suggestion: Searching Problems

I hope this hasn't been asked before - I searched the forum a couple different ways and didn't find the topic. Is it possible to implement some kind of search functionality in the archived problems? For example, one might search for "collatz" or "nim" to find related problems. I know this would help...
by Eventhorizon
Mon Jun 19, 2017 9:00 pm
Forum: Clarifications on Project Euler Problems
Topic: Problem 606
Replies: 8
Views: 1542

Re: Problem 606

Thanks MuthuVeerappanR, V6ph1, and yourmaths. I appreciate your feedback! My guess is I need to better understand how to take advantage of the modular arithmetic part of problems such as this one. "Last 9 digits ..." essentially means answer mod 10^9. So I think I need try to do the S(10^12) example...
by Eventhorizon
Fri Jun 16, 2017 4:23 pm
Forum: Clarifications on Project Euler Problems
Topic: Problem 606
Replies: 8
Views: 1542

Problem 606

I know this is quite soon after the problem was posted, but I am finding myself in recent problems coming up against issues to do with the sheer size of the numbers involved. Trying very hard not to give anything away, here's what I mean regarding this problem: I have found an approach that gives me...
by Eventhorizon
Sun Feb 15, 2015 2:33 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 500
Replies: 2
Views: 998

Re: Problem 500

Message received - Thanks!
by Eventhorizon
Sat Feb 07, 2015 7:49 pm
Forum: Clarifications on Project Euler Problems
Topic: Problem 500
Replies: 2
Views: 998

Problem 500

Can someone confirm that the answer for 2^10,000 divisors, mod 500,500,507 is <removed by moderator>?

(Link to problem added by moderator: Problem 500 (View Problem))
by Eventhorizon
Wed Jan 15, 2014 5:27 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 445
Replies: 10
Views: 2744

Re: Problem 445

Last step, some more interesting retractions: {n=6, a=3, b=0} is a retraction because f(0) = 0 => f(f(0)) = f(0) = 0 and f(2) = f(4) = 0 f(3) = 3 => f(f(3)) = f(3) = 3 and f(1) = f(5) = 3 {n=6, a=4, b=3} is a retraction because f(0) = 0 => f(f(0)) = f(0) = 0 and f(3) = 0 f(2) = 2 => f(f(2)) = f(2) =...
by Eventhorizon
Tue Jan 14, 2014 3:35 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 445
Replies: 10
Views: 2744

Re: Problem 445

Thank you mdean. Next step (I assume the following is so trivial as not to be a spoiler) ... a=1 and b=0 => f(x) = x mod n x <= n, so f(x) = x when 0 <= x < n and f(x) = 0 when x =n Therefore, f(f(x)) = f(x) for all integer values of x, 0 <= x <= n. i.e. f(x) is a retraction for all sets {n, a=1, b=...
by Eventhorizon
Mon Jan 13, 2014 2:06 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 445
Replies: 10
Views: 2744

Problem 445

I think I just don't get modular arithmetic! I would like to get a better understanding without spoiling this problem so I will try baby steps. Can someone verify the following chain of logic: Consider n=12, a=10, b=3 and x=6 f(x) = (10.6 + 3) mod 12 = 63 mod 12 = 3 f(f(x)) = f(3) = (10.3 + 3) mod 1...
by Eventhorizon
Wed Apr 04, 2012 6:18 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 054
Replies: 63
Views: 15896

Re: Problem 054

EDIT: Figured it out, problem with 3 of a kind. PLUS: Suggestion to anyone else trying to verify their ranking algo: see if your counts of each type of hand (2 pair, 3 of a kind, etc) matches expectations - I found I had a count of 3 of a kind that had only a 0.08% probability. You can find the prob...
by Eventhorizon
Thu Feb 02, 2012 3:55 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 369
Replies: 12
Views: 3250

Re: Problem 369

Thank you TripleM, your hint was understood - I see the source of my double-counting! Of course, that doesn't mean I can solve the problem! May I suggest if anyone else is having the same problem as me, simplify the deck to ranks 1-3 and suits H and S, and define a badugi' as 2 cards of different ra...
by Eventhorizon
Tue Jan 31, 2012 11:06 pm
Forum: Clarifications on Project Euler Problems
Topic: Problem 369
Replies: 12
Views: 3250

Re: Problem 369

Still not getting it ... so two questions 1) 5 cards, all different ranks, obviously 2 of same suit, e.g 2H, 6H, 3S, 4D, 5C. Does this only count as 1 badugi-containing hand, even though I can form 2 different badugis: 2H, 3S, 4D, 5C AND 6H, 3S, 4D, 5C? 2) 5 cards containing 1 badugi, can the fifth ...
by Eventhorizon
Tue Jan 31, 2012 6:32 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 369
Replies: 12
Views: 3250

Problem 369

Having trouble making sure I understand a Badugi, because I can't match the 5 card example. My understanding: Regardless the number of cards in the hand (from 4 to 13), I must be able to form at least one set of 4 cards with the following property: Each card in the set of 4 has a different rank and ...