if your using python you can use try:
except:

I didn't get the code. Can someone explain it in depth?

You should return the n-th green number.

Does the diagram work for '100011'? 100011 in base 10 is 35.

No it isn't and it's been discussed before.

There is no looping:

For incrementing sequences, 0 should come after 9, and not before 1, as in 7890.

For decrementing sequences, 0 should come after 1, and not before 9, as in 3210.

In 109, 0 is before 9, opposed to what's written there.

I think you're correct. 109 is interesting, but it's entered as a test case for "close to interesting" (output=1). 109 matches the pattern for the decrementing sequence: 0 comes after 1, but not before 9. Therefore: 2109 and 321098 would also be interesting numbers.

Thank you :)

nope

only one number per row

Can we choose multiple numbers from a row?

read the description carefully again

you need to find the largest path down, starting from the top of the pyramid(first row) till the last(last row)

consecutive refers to going from one 'layer' of the pyramid to another

Can you define "consecutive numbers" clearly?
for example, in the sample example, why is not the last row ([8, 5,9,3]) the answer?

No, it isn't. Why would it be? Check the posts below.

109 is an interesting number, isn't it?