Unit I-Data structures stack & Queue
- 1. STACK & QUEUE Dr. R. Khanchana Assistant Professor Department of Computer Science Sri Ramakrishna College of Arts and Science for Women
- 2. STACK E –Book – Chapter 3 : http://icodeguru.com/vc/10book/books/book1/chap03.htm Stack Tutorial https://www.studytonight.com/data-structures/stack-data-structure
- 3. STACK - EXAMPLES CHAPTER 3 : http://icodeguru.com/vc/10book/books/book1/chap03.htm
- 4. Stacks •The most common data objects in the computer algorithms are Stacks and Queues. •Stacks are dynamic data structures that follow the Last In First Out (LIFO) principle •An Ordered List in which all the insertions and deletions take place at the one end called Top. Bottom
- 5. Stacks Operations: The operation that can be performed on the stack are: CREATE(S) – This Procedure creates S an empty stack. ADD(i,S) – This procedure inserts an element i into the stack S and returns the new stack. DELETE(i,S) – This procedure removes the top most element from the stack S and returns the new stack. TOP(S) – This procedure returns the top most element of the stack S. ISEMT(S) – This procedure returns true, if S is an empty
- 6. STACK Implementations • CREATE ( ) :: = declare STACK(1:n); top 0 • ISEMTS(STACK) :: = if top = 0 then true • else false • TOP(STACK) :: = if top = 0 then error else STACK(top)
- 8. Procedures- Push procedure ADD (item, STACK, n, top) //insert item into the STACK of maximum size n; top is the number of elements currently in STACK// if top n then call STACK_FULL Top top + 1 STACK (top) item end ADD
- 9. Procedures - Pop procedure DELETE (item, STACK, top) //removes the top element of STACK and stores it in item unless STACK is empty// if top 0 then call STACK_EMPTY item STACK (top) Top top - 1 end DELETE
- 10. STACK OPERATIONS
- 13. QUEUE E –Book – Chapter 3 : http://icodeguru.com/vc/10book/books/book1/chap03.htm Queue – Tutorial https://www.tutorialride.com/data-structures/queue-in-data- structure.htm
- 14. Queue - Examples CHAPTER 3 : http://icodeguru.com/vc/10book/books/book1/chap03.htm
- 15. Difference Between Stack & Queue
- 17. Queue – Insertion & Deletion
- 18. Queue Operations • CREATEQ(Q) which creates Q as an empty queue; • ADDQ(i,Q) which adds the element i to the rear of a queue and returns the new queue; • DELETEQ(Q) which removes the front element from the queue Q and returns the resulting queue; • FRONT(Q) which returns the front element of Q; • ISEMTQ(Q) which returns true if Q is empty else false.
- 19. Queue Implementations CREATEQ(Q) :: = declare Q(l:n); front rear 0 ISEMTQ(Q) :: = if front = rear then true else false FRONT(Q) :: = if ISEMTQ(Q) then error else Q(front + 1)
- 20. Queue -Procedure
- 22. Queue – Delete Procedure
- 25. Circular Queue
- 26. Linear Queue Vs Circular Queue
- 28. Dequeue – 3 Elements
- 29. Enqueue – One more element
- 30. Circular Queue • Circular Queue is a bounded queue which implements arrays. • It is better than a normal queue because it will effectively utilize the memory space. • If we have a normal queue and have deleted some elements an empty space is created. • Even if the queue has empty space we cannot insert any new element because the inserting has to be done from one side only(Rear) and deletions has to be done from another side(front). • In case of Circular Queue the Front and Rear are adjacent to each other. Hence we can insert a new element in the empty space (i.e the space from where the element is deleted).
- 32. Circular Queue – ADD Procedure Procedure ADD(i,Q,n,rear) //insert the element i into the Queue rear=(rear+1) mod n; If front = rear then call Queue_Full Q(rear)=item; end ADD
- 34. Circular Queue – Delete Procedure Procedure DELETE(i,Q,front,rear) //insert the element i into the Queue If front=rear then call Queue_Empty front = (front +1) mod n; i=Q(front); end DELETE
- 36. Multiple Stack & Queue
- 37. Multiple Stacks
- 38. Multiple Queues
- 39. Multiple Stack • Boundary condition – B(i) = T(i) iff the i'th stack is empty
- 40. Multiple Stack – Insertion and Deletion