Question

Suppose we have an array-based queue (circular buffer) of size 6:

int data[6];
int front = 0, back = 0;

void enqueue(int x) {
  data[back] = x;
  back = (back + 1) % 6;
}

void dequeue() {
  front = (front + 1) % 6;
}

and we perform the following series of queue operations:

enqueue(1);
dequeue();
enqueue(2);
dequeue();
enqueue(7);
enqueue(3);
enqueue(5);
dequeue();
dequeue();
enqueue(4);
enqueue(6);

Write the state of the queue array after each operation, and at the end, write the values of the front and back variables.

Answer 1

enqueue(1);
queue: [1]
front: 0  
back: 1

dequeue();
Deleted value 1 from queue
queue: []
front: 1  
back: 1

enqueue(2);
queue: [2]
front: 1  
back: 2

dequeue();
Deleted value 2 from queue
queue: []
front: 2  
back: 2

enqueue(7);
queue: [7]
front: 2  
back: 3

enqueue(3);
queue: [7, 3]
front: 2  
back: 4

enqueue(5);
queue: [7, 3, 5]
front: 2  
back: 5

dequeue();
Deleted value 7 from queue
queue: [3, 5]
front: 3  
back: 5

dequeue();
Deleted value 3 from queue
queue: [5]
front: 4  
back: 5

enqueue(4);
queue: [5, 4]
front: 4  
back: 0

enqueue(6);
queue: [5, 4, 6]
front: 4  
back: 1

Final queue: [5, 4, 6]