Stack & queues

Stack & queues

• 1.
  STACKS & QUEUES
• 2.
  STACKS AA ssttaacckkiiss aa rreessttrriicctteedd lliinneeaarr lliisstt iinn wwhhiicchh aallll aaddddiittiioonnss aanndd ddeelleettiioonnss aarree mmaaddee aatt oonnee eenndd,, tthhee ttoopp.. IIff wwee iinnsseerrtt aa sseerriieess ooff ddaattaa iitteemmss iinnttoo aa ssttaacckk aanndd tthheenn rreemmoovvee tthheemm,, tthhee oorrddeerr ooff tthhee ddaattaa iiss rreevveerrsseedd.. TThhiiss rreevveerrssiinngg aattttrriibbuuttee iiss wwhhyy ssttaacckkss aarree kknnoowwnn aass llaasstt iinn,, ffiirrsstt oouutt ((LLIIFFOO)) ddaattaa ssttrruuccttuurreess.. Figure:-Three representations of stacks
• 3.
  Operations on stacks There are four basic operations, stack, push, pop and empty, that we define in this chapter. The stack operation The stack operation creates an empty stack. The following shows the format. Figure:- Stack operation
• 4.
  The push operation The push operation inserts an item at the top of the stack. The following shows the format. Figure:- Push operation
• 5.
  The pop operation The pop operation deletes the item at the top of the stack. The following shows the format. Figure:- Pop operation
• 6.
  The empty operation The empty operation checks the status of the stack. The following shows the format. This operation returns true if the stack is empty and false if the stack is not empty.
• 7.
  Stack ADT Wedefine a stack as an ADT as shown below:
• 8.
  Example 1 Figure1 shows a segment of an algorithm tthhaatt aapppplliieess tthhee pprreevviioouussllyy ddeeffiinneedd ooppeerraattiioonnss oonn aa ssttaacckk SS.. Figure 1:- Example 1
• 9.
  Figure:- Stack implementations
• 10.
  QUEUES AA qquueeuueeiiss aa lliinneeaarr lliisstt iinn wwhhiicchh ddaattaa ccaann oonnllyy bbee iinnsseerrtteedd aatt oonnee eenndd,, ccaalllleedd tthhee rreeaarr,, aanndd ddeelleetteedd ffrroomm tthhee ootthheerr eenndd,, ccaalllleedd tthhee ffrroonntt.. TThheessee rreessttrriiccttiioonnss eennssuurree tthhaatt tthhee ddaattaa iiss pprroocceesssseedd tthhrroouugghh tthhee qquueeuuee iinn tthhee oorrddeerr iinn wwhhiicchh iitt iiss rreecceeiivveedd.. IInn ootthheerr wwoorrddss,, aa qquueeuuee iiss aa ffiirrsstt iinn,, ffiirrsstt oouutt ((FFIIFFOO)) ssttrruuccttuurree.. Figure:- Two representation of queues
• 11.
  Operations on queues Although we can define many operations for a queue, four are basic: queue, enqueue, dequeue and empty, as defined below. The queue operation The queue operation creates an empty queue. The following shows the format. Figure:- The queue operation
• 12.
  The enqueue operation The enqueue operation inserts an item at the rear of the queue. The following shows the format. Figure:- The enqueue operation
• 13.
  The dequeue operation The dequeue operation deletes the item at the front of the queue. The following shows the format. Figure:- The dequeue operation
• 14.
  The empty operation The empty operation checks the status of the queue. The following shows the format. This operation returns true if the queue is empty and false if the queue is not empty.
• 15.
  Queue ADT Wedefine a queue as an ADT as shown below:
• 16.
  Example 2 Figure2 shows a segment of an algorithm tthhaatt aapppplliieess tthhee pprreevviioouussllyy ddeeffiinneedd ooppeerraattiioonnss oonn aa qquueeuuee QQ.. Figure 2:- Example 2
• 17.
  Figure:- Queue implementations
• 18.
  THANK YOU