ArrayQueue

These notes are taken from Goodrich and Tomassia Data Structures and Algorithms in Java, and are the copyright of the authors. Pseudocode 


// Data Structure Invariants:
//   f index of q w/ front of queue, unless queue empty
//   r index of q w/ next open slot
//   f==r means queue is empty

Algorithm size()
   return ( N - f + r ) mod N

Algorithm isEmpty()
   return ( f==r )

Algorithm front() 
   if isEmpty() throw exception
   else return q(f) 

Algorithm dequeue()
   if isEmpty() throw exception
   else return q(f++ mod N)

Algorithm enqueue(o)
   if isFull() throw exception
   else q(r) gets o, and r++ mod N

Algorithm isFull()
   return ( size==N-1 )