In the following code, three processes are synchronized using two semaphores L and R and produce output using the routine putc.

(a) How many D's are printed when these processes run?

(b) Is CABABDDCABCABD a possible output sequence when these processes run?

(c) Is CABACDBCABDD a possible output sequence when these processes run?

semaphore L. value = 3, R.value = 0; /* initialization */ /* Process 1 */ /* Process 2 */ L1: L2: wait (L); putc ('C'); signal (R); goto L1; wait (R); putc ('A'); putc ('B'); signal (R); goto L2; /* Process 3 */ L3: wait (R); putc ('D'); goto L3;