I've passed 20% of test cases: 0, 1, 2 and there is a question about test case #3. We have 49945 and 49523 as input data and I expect the amount of combination have to be close to each other, but there is a huge difference: 62663303 vs 832450948. Is it ok?

for the second test case i.e 4 tiles. While painting 2 tiles why not GWWG case is considered if GWGW and WGWG are considered.

@ramiroluz

No.

Be aware of that "Indices of green fields must form an arithmetic progression".

In your example the progression (difference from index to index) is first "1" and then "2" and vice versa.

So if the progression between the indices of green fields is not constant, the case has to be excluded.

WGGW -> difference between (green) indices is always "1". -> valid

GGWG -> difference between first and second index is "1", but from second to third index the difference is "2" -> invalid.

:)

I believe there is some missing combinations, or I didn't get the point.

It is not possible to paint 4 tiles this way:

• 1 - G, 2 - G, 3 - W, 4 - G
• 1 - G, 2 - W, 3 - G, 4 - G