Euler – Coder.si

Comfortable distance

There are N seats in a row. N people come after each other to fill the seats according to the following rules:

If there is any seat whose adjacent seat(s) are not occupied take such a seat.

If there is no such seat and there is any seat for which only one adjacent seat is occupied take such a seat.

Otherwise take one of the remaining available seats.

We can verify that T(10) = 61632 and T(1 000) mod 100 000 007 = 47255094.

Find T(1 000 000) mod 100 000 007.