1.Let A and B be two semaphores initialized to 1, whether this following code has problem, if so, which problem and explain your answer

P₀ P₁

wait(A); wait(B);

wait(B); wait(A);

signal(A); signal(B);

signal(B); signal(A);

2.Philosophers spend their lives thinking and eating . These Philosophers dont interact with their neighbors, occasionally try to pick up 2 chopsticks (one at a time) to eat from bowl and they need both to eat, then release both when done

In the case of 5 philosophers, Semaphore chopstick [5] initialized to 1

Does the following codes have problem? If so, which kind(s) problem(s)? How to deal with the problem(s)?

do {

wait (chopstick[i] );

wait (chopStick[ (i + 1) % 5] );

// eat

signal (chopstick[i] );

signal (chopstick[ (i + 1) % 5] );

// think

} while (TRUE);