Size of Circular Queue
Suppose that the queue consists of elements $Q[a],\ldots,Q[b]$, where $Q = Q[1],\ldots,Q[n]$ is an array of length $n$. If $a \leq b$ then the queue contains $b-a+1$ elements, and if $a &gt; b$ then the queue contains $b-a+1+n$ elements.