you can't, because it has no length. re-read the Remarks portion of the description

There is no issue with the tests, because:

[2, 2, 0, 0, 0, 1, 2]
[1, 1, 1, 0, 0, 2, 1]
[1, 1, 1, 2, 0, 1, 2]
[1, 2, 2, 2, 0, 1, 2]
[2, 2, 1, 2, 2, 2, 1]
[1, 1, 2, 2, 1, 2, 1]

Where 2 is yellow, see the 4th column.

It is red, here is how:
B0 - red, C0 - red, D0 - red, E0-red
subscript 0 implies ground/first row from bottom.

Hi,

All outputs are correct, I can assure you. ;)
Use pen and paper to simulate the board, you'll see.

Note: "issues", on CW are reserved for dysfunctionning katas/wrong tests/... Open one only when you can actually prove that you're facing one of those. Here, you didn't prove the expected result is incorrect (and I can assure you it is correct), hence, use the "Question" instead.

cheers

System.out.println

Are you sure you're not accumulating the inputs or logs?

If i'm printing the word then its showing: ZlW849R45?a`0f>Q2+6*ZZ{NS1h0?N%V78OaMk4^71><73k4l iQNM?*aU2`T(g98V8hO8

So what's the problem then?

You should ask google that question, not here ;)

I'm quite sure about my code.

XD
In no time, you'll realize you shouldn't ;) (You have no idea how often this happens ;) )

Is there anyway to know the imput?

sure: System.out.println(Arrays.toString(input))

Not an issue. [I@21507a04 is not the array, but its address (or whatever they call it in Java).