//Assignment # 4 Question 1
//Due Oct 14,1999

Conditions necessary and sufficient for a sequence of insert and remove operations on a single: 

1a) Empty queue to leave the queue empty without causing underflow:
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1) One of the location in queue is reserved and is never filled.
Queue Locations: 0 1 2 3 4 5
Items in Queue:       A

2) The front pointer points to a position one less than the acutal element in queue.
Queue Locations: 0 1 2 3 4 5
Items in Queue:       ABCDE
Front Pointer:0
Rear Pointer:5

3) With above two conditoins. Front = Rear only if no elements are present in the Queue.
This condition indicates Empty queue. All deQueue operations must see if front=rear before 
dequeueing.

1b) Conditions to leave non-empty queue unchanged:
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Consider a queue implemented using Array with MAX = 4
Queue Slots : 	0	1	2	3
Items in Queue:		A	B	C
Front=0
Rear=3
Here Rear=MAX-1 element. Addition of another item will result in operation rear=0.
Front must be checked before this operation as rear=front=0 will render empty queue.