### Problem 155

Posted:

**Sat Mar 21, 2009 12:49 pm**Can anybody please confirm me if the values D(4) = 15 and D(5) = 35 are correct.

thanks in advance.

thanks in advance.

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Posted: **Sat Mar 21, 2009 12:49 pm**

Can anybody please confirm me if the values D(4) = 15 and D(5) = 35 are correct.

thanks in advance.

thanks in advance.

Posted: **Sat Mar 21, 2009 12:52 pm**

Yes, they are correct.

Posted: **Sat Mar 21, 2009 1:13 pm**

Thanks Tommy. I really cannot understand the problem with my algorithm. Is D(10) = 2491.

Posted: **Sat Mar 21, 2009 1:15 pm**

Unfortunately, it's wrong

Posted: **Sat Aug 20, 2011 9:01 pm**

I don't get it either...

Is it wrong to think, that the only new capacitor combinations are the ones from the previous, with max number of capacitors, + a series and a paralel with a new 60 microfahrad capacitor?

ex

if we have 2 2 capacitor combinations, then there will be 4 extra in the next, and 8 extra in the next and so on?

I cannot imagine how else a combination would be made, but then my D(5) = 31, and i don't see where the 4 extra comes from

Is it wrong to think, that the only new capacitor combinations are the ones from the previous, with max number of capacitors, + a series and a paralel with a new 60 microfahrad capacitor?

ex

if we have 2 2 capacitor combinations, then there will be 4 extra in the next, and 8 extra in the next and so on?

I cannot imagine how else a combination would be made, but then my D(5) = 31, and i don't see where the 4 extra comes from

Posted: **Sat Aug 20, 2011 9:52 pm**

Hint: 5 = 1+4 = 2+3Schwein wrote:I cannot imagine how else a combination would be made, but then my D(5) = 31, and i don't see where the 4 extra comes from

Remember also that we only care about the different values - some values can be made in several completely different ways, so that is another reason why it won't be a simple doubling sequence.

Posted: **Sat Aug 20, 2011 10:56 pm**

I had the part covered, that some values might be equal(turned out none of them were, when i just added one in series, and one in paralel, for each combo), the only thing i don't understand, is why that does not give me all the different combinations makeable...

Posted: **Sat Aug 20, 2011 11:10 pm**

How about combining larger, 'composite' capacitors in series or parallel? (This is what hk meant above as well)Schwein wrote:the only thing i don't understand, is why that does not give me all the different combinations makeable...

Think about $1 = \frac1{1+1}+\frac1{1+1}$.

Posted: **Sat Aug 20, 2011 11:21 pm**

Ahhhhh, thank you were much the both of you, I see now where my logic fails ^^

Posted: **Sun Jan 12, 2014 3:45 pm**

It seems I can't get it right... I get the correct results for D(4) and D(5). Then D(6) = 76 and D(10) = 2147. Are these values correct?

Posted: **Sun Jan 12, 2014 6:44 pm**

No.Erf_Erf wrote:It seems I can't get it right... I get the correct results for D(4) and D(5). Then D(6) = 76 and D(10) = 2147. Are these values correct?

Posted: **Sun Jan 12, 2014 11:21 pm**

I just found the annoyingly trivial and almost invisible mistake in my code, and finally got the correct answer.

Posted: **Tue Jul 09, 2019 6:00 pm**

Hi all,

Could I ask for two pieces of input here:

1) D(13) is a 5-digit figure starting with a 4 and ending in an even digit - is that correct?

2) I'm using float values in C and my suspicion is that my solutions turns out wrong because of a precision issue. I've tried (long) double but the result is no more convincing. Should I try to go for the alternative of defining and manipulating fractions (as Wodehouse would have said: I've just had a look at what my mind is doing, and it turns out: it boggles!) or should I rather look for something else - my choice of value for the capacitance for example.

Cheers,

Claude

Could I ask for two pieces of input here:

1) D(13) is a 5-digit figure starting with a 4 and ending in an even digit - is that correct?

2) I'm using float values in C and my suspicion is that my solutions turns out wrong because of a precision issue. I've tried (long) double but the result is no more convincing. Should I try to go for the alternative of defining and manipulating fractions (as Wodehouse would have said: I've just had a look at what my mind is doing, and it turns out: it boggles!) or should I rather look for something else - my choice of value for the capacitance for example.

Cheers,

Claude

Posted: **Fri Jul 12, 2019 7:55 am**

Claude,

to answer your first question:

D(13) is indeed a 5-digit figure but it starts with 3 and ends with an odd digit.

hth

Jochen

to answer your first question:

D(13) is indeed a 5-digit figure but it starts with 3 and ends with an odd digit.

hth

Jochen

Posted: **Fri Jul 12, 2019 9:03 am**

Right, back to the drawing board then ...

Thanks for getting back though!

Thanks for getting back though!

Posted: **Wed Jul 24, 2019 1:11 pm**

Right, got there in the end, although the program takes about 40 seconds to come up with the answer...

Thanks for the help again!

Claude

Thanks for the help again!

Claude

Posted: **Wed Apr 22, 2020 5:48 pm**

Hello,

I am trying to resolve this problem in Hacker Rank, but my solution only is successfull from 1 until 4.

For n = 5 and C=60, I got 31 results:

12, 15, 17.1429, 20, 22.5, 24, 25.7143, 30, 34.2857, 36, 37.5, 40, 42.8571, 45, 48, 60, 75, 80, 84, 90, 96, 100, 105, 120, 140, 150, 160, 180, 210, 240, 300

Can someone show me other different numeric result?

Thanks

I am trying to resolve this problem in Hacker Rank, but my solution only is successfull from 1 until 4.

For n = 5 and C=60, I got 31 results:

12, 15, 17.1429, 20, 22.5, 24, 25.7143, 30, 34.2857, 36, 37.5, 40, 42.8571, 45, 48, 60, 75, 80, 84, 90, 96, 100, 105, 120, 140, 150, 160, 180, 210, 240, 300

Can someone show me other different numeric result?

Thanks

Posted: **Wed Apr 22, 2020 6:33 pm**

50 is missing:

r(60,60) = 30

r(60,60,60) = 20

p(r(60,60),r(60,60,60)) = 50

r(60,60) = 30

r(60,60,60) = 20

p(r(60,60),r(60,60,60)) = 50