Suppose a circular queue of capacity (n - 1) elements is implemented with an array of n elements. Assume that the insertion and deletion operations are carried out using REAR and FRONT as array index variable respectively. Initially, REAR = FRONT = 0. The conditions to detect queue empty and queue full are

The Correct answer is  EMPTY : REAR == FRONT and FULL : (REAR + 1) mod n == FRONT

Key Points A circular queue is a queue whose last position is connected back to the first position.

• ENQUEUE – It is the operation to insert elements into the queue.
• DEQUEUE – It is the operation to delete elements from the queue.

After inserting an element in the last position, the next element again gets inserted into the first position.

EXPLANATION:

• Given, Rear = Front = 0
• Here, the Rear is used to insert elements & the front is used to delete elements.
• To check full condition in queue:
  • (Rear + 1) % n == Front
• Example: Consider queue is full that means Rear = 6, front = 0, n = 7
  • (6+1) % 7 = 7 % 7 = 0
• To check empty condition in queue:
  • Rear == Front
• Example: Consider queue is empty that means Rear = 0, front = 0, n = 7
  • Rear = Front = 0

Hence, the correct answer is “option 1”.