Stack and Queue (brief)

Stack and Queue (brief)

• 1.
  STACK, QUEUE SANJAY SAHA
• 2.
  STACK: WHAT &WHY  Collection of elements of same type  LAST IN FIRST OUT = LIFO  The last elements that is put in it, is the first one to get out of it!  Real life examples:  Plate stack  Book shelf  In computer science studies:  Recursion, function calls  Infix to prefix, postfix evaluation  Operating systems
• 3.
  STACK: VISUAL SIMULATION B A D C B A C B A D C B A E D C B A top top top top top A Input: A, B, C, D, E popped
• 4.
  STACK: EXAMPLE  Factorial 6! = 6 x 5! = 6 x 5 x 4! = … = 6 x 5 x 4 x 3 x 2 x 1 Recursive solution int fac(int numb){ if(numb<=1) return 1; else return numb*fac(numb-1); } fac(1) fac(2) fac(3) fac(4) fac(5) fac(6) 2 x 1 3 x 2 x 1 4 x 3 x 2 x 1 5 x 4 x 3 x 2 x 1 6 x 5 x 4 x 3 x 2 x 1
• 5.
  QUEUE: WHAT &WHY  FIRST IN FIRST OUT = FIFO  The first elements that is put in it, will be the first one to get served!  Real life examples:  Ticket queue  Restaurant  In computer science studies:  Threads  CPU job scheduling  Sorting
• 6.
  A B A C B A D C B A D C Brear front rear front rear front rear front rear front QUEUE: VISUAL SIMULATION Input: A, B, C, D, E
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  QUEUE: EXAMPLE  CircularQueues  The rear of the queue can be behind the front  Effective time utilization b c d FrontRear b c d FrontRear e f e fg
• 8.
  SUMMARY
• 9.
  Stack and queue SanjaySaha University of Dhaka Thank you!