GATE Overflow Test Series | Operating Systems | Test 1 | Question: 7

Question

A counting semaphore is initialized to $X$. Then $13\; P\; \text{(wait)}$ operations and $25\;V \; \text{(signal)}$ operations are completed on this semaphore. If the final value of semaphore is $8$, then the value $X$ will be _______

Answer 1

Each signal operation increments the semaphore and each wait operation decrements it. Thus we have $X - 13 + 25 = 8 \implies X = -4$