How to make sure that all the values in an array are different?

[simondex]

Hi, Everyone!

How could I make sure that nine values (from 0 to N) are all different
without writing too many loops? I am not afraid of statistical
parameters (e.g. coefficient of variation, etc.)

Thank You Very Much.

Truly Yours, Simon Dexter

[Josh Mcfarlane]

si******@yahoo.com wrote:

Hi, Everyone!

How could I make sure that nine values (from 0 to N) are all different
without writing too many loops? I am not afraid of statistical
parameters (e.g. coefficient of variation, etc.)

Thank You Very Much.

Truly Yours, Simon Dexter

What's wrong with loops? With only 9 values you wouldn't be taking that
much of a performance hit to start with the first value, compare it to
the remaining 8, then the 2nd value, remaining 7, etc.

If that's not acceptable though, I'm sure you can find some built in
algorithms to test for uniqueness of values.

unique seems like a good STL candidate, however, you'd have to have
your values in a sorted container in order to use it.

[Pete Becker]

Josh Mcfarlane wrote:

unique seems like a good STL candidate, however, you'd have to have
your values in a sorted container in order to use it.

A sorted container isn't needed. All that's needed is a sequence that's
sorted.

--

Pete Becker
Dinkumware, Ltd. (http://www.dinkumware.com)

[benben]

<si******@yahoo.com> wrote in message
news:11*********************@g14g2000cwa.googlegro ups.com...

Hi, Everyone!

How could I make sure that nine values (from 0 to N) are all different
without writing too many loops? I am not afraid of statistical
parameters (e.g. coefficient of variation, etc.)

Thank You Very Much.

Truly Yours, Simon Dexter

Use a set

[simondex]

What is STL (concerning my question)?

[Ken Wilson]

On 18 Jul 2005 19:51:44 -0700, si******@yahoo.com did courageously
avow:

What is STL (concerning my question)?

It is the C++ Standard Template Library the compile vendor supplies
with your compiler. It is the place for generic everything,
containers, iterators for containers, algorithms. If you're asking
that question be ready for some heady stuff.

Ken Wilson
"Coding, coding, over the bounding main()"

[Zorro]

Actually, it is only two loops, and the complexity is n*n. Write a
function that receives your array. If you do not want to to change the
array, make a local one and copy your array to it.

Now, do a selection sort, but return at any time when the test for
equality of items in the array is true.

Suppose you return 0 on equality, otherwise return 1 at end of function
when sort completes, meaning all elements are different.

The test could look like this:

if (a[i] == a[j]) return 0;
else if (a[i] > a[j]) do-selection-sort

and if you never returned from inside the loops (the equality), now
return 1.

Hope it helps.

Regards,
Dr. Z.
Chief Scientist
zo****@ZHMicro.com
http://www.zhmicro.com
http://distributed-software.blogspot.com

[Zorro]

Actually, it is only two loops, and the complexity is n*n. Write a
function that receives your array. If you do not want to to change the
array, make a local one and copy your array to it.

Now, do a selection sort, but return at any time when the test for
equality of items in the array is true.

Suppose you return 0 on equality, otherwise return 1 at end of function
when sort completes, meaning all elements are different.

The test could look like this:

if (a[i] == a[j]) return 0;
else if (a[i] > a[j]) do-selection-sort

and if you never returned from inside the loops (the equality), now
return 1.

Hope it helps.

Regards,
Dr. Z.
Chief Scientist
zo****@ZHMicro.com
http://www.zhmicro.com
http://distributed-software.blogspot.com