A linked list Queue
A circularly linked list is used to represent a queue as shown in the figure above. A single variable
is used to access the Queue. To which node should
point such that both the operations enQueue and deQueue can be performed in
time?
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1 solution
The deQueue operation requires access to the Head node (to return to the caller) and access to the Rear node (to update the Rear node's pointer to point to the new Head node).
The enQueue operation requires access to the Rear node (to update to the Rear node's pointer to point to the new Rear node).
If Q points to the Rear node, access to the Rear node is O(1) (one step: dereferencing the Q pointer), access to the Head node is also O(1) (two steps: dereferencing the Q pointer and then dereferencing the Rear node's pointer to the Head node).