@Amir: Presumably, since these are digits in a number, they are
bounded on the bottom by 0 and on the top by radix-1. So in decimal,
if a digit is 7 and the absolute difference between it and the next
digit is 3, there is only one possibility for the next digit, 7-3 = 4,
since 7+3 is too large. So only some subset of the 2^(n-1)
combinations of addition and subtraction may be possible.

Dave

On Dec 13, 4:15 am, Amir hossein Shahriari
<amir.hossein.shahri...@gmail.com> wrote:
> actually there are infinite number of sequences that match it
> for example if the absolute differences are 3 2 5 1
> one possible sequence is 6 3 5 0 1 one other is 7 4 6 1 2 or 8 5 7 2 3
> and you can add any integer value to all elements and the result will still
> be valid
> actually you can start with any number and and then the second number will
> be equal to the first number that you chose plus/minus the first absolute
> difference and so on
>
> so if we are given the first element of the sequence there are 2^(n-1) ways
> to find a valid sequence because for each absolute difference we can either
> add the absolute difference to the last sequence element or subtract the
> absolute difference from it
>
>
>
> On Mon, Dec 12, 2011 at 9:01 PM, KAY <amulya.manches...@gmail.com> wrote:
> > If for a number n digits long, the absolute difference between
> > adjacent digits is given, how to find out the number of different
> > numbers with these absolute differences ?
>
> > for eg,
> > if n=5
> > and the absolute differences are
> > 3 2 5 1
> > then 1 possible number is
> > 6 3 5 0 1    (because |6-3|=3,|3-5|=2 and so on...)
>
> > How many such numbers will be there?
>
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