Problem 581

A place to air possible concerns or difficulties in understanding ProjectEuler problems. This forum is not meant to publish solutions. This forum is NOT meant to discuss solution methods or giving hints how a problem can be solved.
Forum rules
As your posts will be visible to the general public you
are requested to be thoughtful in not posting anything
that might explicitly give away how to solve a particular problem.

This forum is NOT meant to discuss solution methods for a problem.

In particular don't post any code fragments or results.

Don't start begging others to give partial answers to problems

Don't ask for hints how to solve a problem

Don't start a new topic for a problem if there already exists one


See also the topics:
Don't post any spoilers
Comments, questions and clarifications about PE problems.
Post Reply
User avatar
Oliver1978
Posts: 166
Joined: Sat Nov 22, 2014 9:13 pm
Location: Erfurt, Germany

Problem 581

Post by Oliver1978 »

The problem and its description are pretty much straight forward. A brute-force algorithm may work for p-smooth numbers with small p. I've tried something different and tried several sets of primes [2, 3...]. Following the description of this problem, might I ask if I'm right with the following: the sum of Hamming numbers being 3 digits long ending with ..1; also for 7-smooth numbers the result is 4 digits long ending with ..3; and furthermore for 11-smooth numbers the result is 5 digits long and ending with ..91.

Is this correct so far?
49.157.5694.1125

v6ph1
Posts: 120
Joined: Mon Aug 25, 2014 6:14 pm

Re: Problem 581

Post by v6ph1 »

Yes - it is.
Image

mdean
Posts: 156
Joined: Tue Aug 02, 2011 1:05 am

Re: Problem 581

Post by mdean »

Does this solution really fit into a 64-bit integer? Because I foresee having to test some huge numbers for this problem. For now, I'll start small and work my way up.
Image

v6ph1
Posts: 120
Joined: Mon Aug 25, 2014 6:14 pm

Re: Problem 581

Post by v6ph1 »

Yes - The total fits into 42 bit.
The intermediates of your algorithm should also fit. - If not, think of it.
Image

AdamCapo
Posts: 2
Joined: Mon May 08, 2017 5:23 pm

Re: Problem 581

Post by AdamCapo »

Hello,

I was hoping someone could help me out by giving me some more test cases to help me see where I am going wrong.

From another site, I was able to get the solutions for 2,3,5,7,11,13 and 17 smooth numbers (snipped by moderator) and my code works fine for all them. However, somewhere between the 17-smooth solution and the 47-smooth solution there is a problem in my code that I can't seem to figure out. Based on the previous posts I don't believe it is a memory issue, but I could be wrong.

Thanks!

User avatar
hk
Administrator
Posts: 10697
Joined: Sun Mar 26, 2006 9:34 am
Location: Haren, Netherlands

Re: Problem 581

Post by hk »

This forum isn't meant to provide (partial) answers to problems.
Image

v6ph1
Posts: 120
Joined: Mon Aug 25, 2014 6:14 pm

Re: Problem 581

Post by v6ph1 »

@AdamCapo:
The solutions, you provided works all with 32Bit Integers.
But numbers which are smooth to a higher prime need 64Bit.
Image

AdamCapo
Posts: 2
Joined: Mon May 08, 2017 5:23 pm

Re: Problem 581

Post by AdamCapo »

I apologize for asking for information that wasn't allowed. I had seen in other parts of the forum people asking/receiving test values, so I thought I was OK.

As for my error, it turned out to be a basic misunderstanding of how to use a theorem. Since my limit was so high, it didn't cause an issue for lower p-smooth numbers, but became apparent higher up.

User avatar
hk
Administrator
Posts: 10697
Joined: Sun Mar 26, 2006 9:34 am
Location: Haren, Netherlands

Re: Problem 581

Post by hk »

AdamCapo wrote:
Tue May 09, 2017 1:45 pm
I apologize for asking for information that wasn't allowed. I had seen in other parts of the forum people asking/receiving test values, so I thought I was OK.
Next time please read the content of the pink box at the top of the page.
Image

Post Reply