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Que. There are three processes P1, P2 and P3 sharing a semaphore for synchronising a variable. Initial value of semaphore is one. Assume that negative value of semaphore tells us how many processes are waiting in queue. Processes access the semaphore in following order:

(a) P2 needs to access
(b) P1 needs to access
(c) P3 needs to access
(d) P2 exits critical section
(e) Pi exits critical section

The final value of semaphore will be:
a. 0
b. 1
c. -1
d. -2
Ashu :(May 15, 2019) I want to know answer explanation
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Shri :(June 06, 2019) Needs to access the critical section means P( ) operation on Semaphore
exit critical section means V( ) operation on Semaphore.
given that intial value of semaphore = 1
final value of semaphore = Initial value - No.of P() operations + No.of V() operations
= 1-3 +2
= 0
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