Did someone like an interesting challenge?

Question

We have a jagged array (entered by user): " jArray" that contain the three arrays:

jArray[0][ ]={"A", "B", "C"};
jArray[1][ ]={"D"};
jArray[2][ ]={"E", "F"};

write a method that receive jArray as argument and returns what following (in the same order):

ADE
ADF
BDE
BDF
CDE
CDF

The method must be reusable and must allows a jagged array of any length: "jArray[n][m]".

Tip: recursivity could help.

Answer 1

You simply use nested for loops
I don't know C# but still
How is that even a challenge?

Answer 2

Hello, to say it that way sounds like explaining that to make a house you have to use cement and bricks without adding anything else. It is not as easy as it may seem at first. I've been through the nested loops when I was looking for the solution, but they have not been enough, although they are obviously necessary. I forgot to mention that I already have the solution (using LINQ). I would just like to see if there are other algorithms and what they are (including in others languages like java ;) )

Answer 3

Ok, this is part of the code I've found on Internet and it work very well.
Also I've another version (totally mine) that work non-recursively and only with arrays.

static IEnumerable<IEnumerable<T>> CartesianProduct<T>(this IEnumerable<IEnumerable<T>> sequences)
{
// base case:
IEnumerable<IEnumerable<T>> result = new[] { Enumerable.Empty<T>() };
foreach (var sequence in sequences)
{
// don't close over the loop variable
var s = sequence;

// recursive case: use SelectMany to build the new product out of the old one
result =
from seq in result
from item in s
select seq.Concat(new[] { item });
}
return result;
}