Thanks. I guess that means back to the drawing board for me :)

Is

+-+ +-+
| | | |
| +-+ |
|     |
+-----+

valid input?

How about

+-----+
|     |
| +-+ |
| | | |
| +-+ |
|     |
+-----+

?

"EDIT: I have found that 1551121e25 is 25 factorial."

No, it's not.

Thanks.

"I've preload a method open, usage is open(row,column) (for Java users: Game.open(int x, int y))."

Should that be "Game.open(int y, int x)"?

(or "Game.open(int row, int column)" for consistency)

https://explainxkcd.com/wiki/index.php/195:_Map_of_the_Internet

Don't use doubles.

"represented in this case with two arrays"

Sorry, that statement is false. Let's look at the first example given by you:

array = [[1,2,3],
         [4,5,6],
         [7,8,9]]

I count 4 arrays: 1 outer array, and 3 inner arrays. Each of the inner arrays represents a row of the matrix.

How many rows does the 0x0 matrix have? Zero. How many inner arrays should the representation of the 0x0 matrix have?

Thank you.

"You can optionally include or dis-include punctuation."
"Don't filter out the punctuation as they are a part of the string."

So, which is it?

Probably too late to change this now, but... wouldn't map(f, list) be more idiomatic?

It would help if you separate the definition of ludic numbers and the example.

Why do you define 1 to be ludic? If I remove every first element from the list, nothing remains. This would mean that if 1 is a Ludic number, 1 is the ONLY Ludic number.

I believe there is an error in your example: When you remove 5 from the list, shouldn't you remove 19, too?

Um, yes. And how many rows does the empty matrix have?