Suppose the C-SCAN algorithm is used while the following I/O queue has accumulated for the cylinders in the following list:   91, 176, 31, 115, 7, 117, 58, 60   If the head is at the beginning of cylinder 46 (i.e. cylinder 46 has just been served by moving to the last cylinder, cylinder 199),   what is the fourth cylinder to serve in the queue

Implement a queue Q with two stacks S1 and S2, so that the stacks that operate together as a queue may perform the operations ENQUEUE(Q, X) and DEQUEUE(Q, Y), where Q appears to be a queue and X is the element to be inserted into Q and Y is the element to be removed from Q. Assume that the ADT operations PUSH, POP, and EMPTYSTACK are only available for stacks.Show how your technique works on a list a, b, c, which will be utilised as a queue by the stacks S1 and S2.

Problem 2. In Project 6 you are required to use pthreads condition variables and mutexes to synchronize accesses to shared variables in your priority queue implementation. Ben Bitdiddle wants to try (on his own) to do it using semaphores instead. As in Project 6, the “next" operation returns the highest-priority item in the queue; if the queue is empty, it blocks until the queue becomes non-empty. The “insert" operation places an item in the queue, and if the queue went from empty to non-empty, it signals any waiting threads. Ben's implementation uses a (global) semaphore to count the number of items in the queue, and uses the Bryant and O'Hallaron "P()" and "V()" wrapper functions (see text) to decrement and increment it. He declares a global sem_t list_size and initializes it with sem_init(&list_size,0,0). The global variable list_head points to the first item in the list and is initially NULL. a. In Ben's first attempt, the pq_next() function does this: P(list_size); // block until…

Implement a queue using two stacks. Your solution should have a time complexity of O(1) for enqueue and dequeue operations.