Also of note, this channel is in large part made up of university
lecturers, researchers, and PhD students. I really wouldn't be
surprised if one of them were to notice the assignment they set
cropping up here.
Bob
On 12 Aug 2006, at 13:58, Thomas Davie wrote:
Hi,
While this is an interesting question, the haskell mailing list
is not really the appropriate place to ask it.
Questions here should be of the form of:
• How do I work this feature of Haskell
• What the hell does this error mean
• Wouldn't it be cool if Haskell did this?
• Is there a <insert dev tool here> for Haskell?
• Is there a <insert library here> library for Haskell?
They shouldn't be of the form:
• Can you do my university assignement for me?
• Can you write this piece of code for me?
Although, you could probably get away with:
• Here's a solution to this problem, how do I optimise it?
Bob
On 12 Aug 2006, at 13:23, Mohammad Mehdi Bezyan wrote:
Hello All
There are 2 questions for my project and I need to aswer them as
soon as possible. The answers need to be written in Haskell using
recursive methods.
The questions are the following:
Number 1:
The set of n-combinations of a set S is the set of subsets of S of
size n. Write a function combs :: Int -> [a] -> [[a]] which,
representing sets as lists, calculates n-combinations of a given
list. For example, combs 3 [1,3,5,6,9] is [[1,3,5],[1,3,6],[1,3,9],
[1,5,6],[1,5,9], [1,6,9],[3,5,6],[3,5,9],[3,6,9],[5,6,9]]
Within each combination, the n values should appear in the same
order as they appear in the original list (so, for example,
[1,5,3] should not appear instead of [1,3,5] in the result for
combs 3 [1,3,5,6,9]). But the list of combinations may appear in
any order (ie, [1,3,5] need not appear first in the result of
combs 3 [1,3,5,6,9]). You may assume that the list argument to
combs does not contain duplicate members.
Number 2:
Given a list of lists, a list is in the Cartesian product of them
if it contains one member from each of them. Write a function
cart :: [[a]] -> [[a]] which calculates this. For example, cart
[[1,2], [4], [7,8,9]] is [[1,4,7],[1,4,8],[1,4,9],[2,4,7],[2,4,8],
[2,4,9]]
Each member of the Cartesian product must appear in the
appropriate order: eg, in [1,4,7] above, 1 appears first, then 4,
then 7, because 1 is from the first input list [1,2], 4 is from
the second input list [4], and 7 is from the third input list [7].
The list of members of the Cartesian product may appear in any
order (ie, [1,4,7] need not appear first in the list).
It would be very much appreciated if you could help me or provide
me with some code, please. I need them very soon.
Thanks!
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