Optimal seat booking allocation algorithm [on hold]

If a train travelling from station A to E with station B, C, D in between with 2 seats (seat 1 and seat 2).

Seat 1 is not booked for the whole journey.

Seat 2 is booked from station A to B and station D to E.

Booked as ( '-' : Empty and '#' : Booked )

Seat 1 : A ---------------------------------------------------------- E

and

Seat 2 : A ############ B -------------- C ---------- D ############# E

I need a best way or an algorithm so that if a booking request comes for station B to C or C to D seat 2 should be booked by the system so that any other booking for the whole route should be allocated seat 1.

Thanks in advance!