I have problems understanding the exact question.

Do the piles need to have different counts of plates:

1) before the new plates are added,

2) added to each pile,

3) after new plates are added

4) all or some of the above - which? _____________

Thanks.

## Problem 688

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Comments, questions and clarifications about PE problems.

### Re: Problem 688

What "new plates"? You take n plates and divide them into k piles. For each calculation of f(n,k), the total number of plates is fixed.

### Re: Problem 688

"We stack n plates into k non-empty piles where each pile is a different size."

So, the new plates are n, and the k piles are NOT empty, therefore old or existing.

EDIT: Or am I reading that wrong? - Does it simply mean that I have to place at least one plate on each pile, leaving none empty, and that the k piles are empty before you place the plates?

So, the new plates are n, and the k piles are NOT empty, therefore old or existing.

EDIT: Or am I reading that wrong? - Does it simply mean that I have to place at least one plate on each pile, leaving none empty, and that the k piles are empty before you place the plates?

### Re: Problem 688

You might be reading "We stack n plates into k non-empty piles" as "We stack n plates

It might be the "non-empty" that's tripping you up. This is describing the piles after the stacking, not before. It's not something you'd say in every-day speech, but in maths a pile could contain zero plates, and that case must be excluded for this problem.

It might be better worded "We divide n plates into k non-empty piles".

*onto*k non-empty piles", which (to me at least) has a quite different meaning. We start with nothing but n plates. Stacking takes place. Then we have k piles, none of which are empty. The question is concerned with this final state: a total of n plates in k piles (with no two piles having the same number of plates). How they got there doesn't matter.It might be the "non-empty" that's tripping you up. This is describing the piles after the stacking, not before. It's not something you'd say in every-day speech, but in maths a pile could contain zero plates, and that case must be excluded for this problem.

It might be better worded "We divide n plates into k non-empty piles".

### Re: Problem 688

Thank you for clarifying DJohn.

The language had me misunderstanding the task. I would have preferred something like "Stack n plates in k piles. No pile must remain empty."

Anyway, I understand the question now, so I will now see if I can solve it.

The language had me misunderstanding the task. I would have preferred something like "Stack n plates in k piles. No pile must remain empty."

Anyway, I understand the question now, so I will now see if I can solve it.

### Re: Problem 688

Minor clarification:

The problem text reads:

It is possible to divide 10 into 5 non-empty piles, 10 = 2 + 2 + 2 + 2 + 2. It is impossible to divide 10 into 5 non-empty piles with different number of plates.

Should we clarify this in the problem statement?

The problem text reads:

**It is impossible to divide 10 into 5 non-empty piles and hence f(10,5)=0.**It is possible to divide 10 into 5 non-empty piles, 10 = 2 + 2 + 2 + 2 + 2. It is impossible to divide 10 into 5 non-empty piles with different number of plates.

Should we clarify this in the problem statement?

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- RobertStanforth
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### Re: Problem 688

Hello,

I'm able to compute the exact S(100) value with a simple algorithm and an optimized algorithm. My simple algorithm gives me the same result as the optimized one till 10

Thanks

I'm able to compute the exact S(100) value with a simple algorithm and an optimized algorithm. My simple algorithm gives me the same result as the optimized one till 10

^{6}or 10^{8}. Anyway, the solution for 10^{16}is wrong. Could you provide S(10^{6}) or S(10^{8}) in order to be able to trouble shoot my simple & optimized algorithm as I assume there should be a special case that I've not taken into account and that is not visible in S(100).Thanks