This can be considered under two conditions,
first
let there is only one process(or odd number of processes), then there are two possibilities that it might want to access code A or code B(this is process process synchronization problem not the critical section) and they can be accessed alternatively is the restriction, then the output could be either 1(or ending with one).
second
let there are even number of processes then there should be alternate 1's and 0's.
Now, the language of the code would be,
- in terms of english(which is more precise here) -- every 0 is followed by a 1.
- in terms of expression(it'll depend on number of processes) -- 1(01)* + (10)*