Deque and its applications
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This document discusses double-ended queues or deques. Deques allow elements to be added or removed from either end. There are two types: input restricted deques where elements can only be inserted at one end but removed from both ends, and output restricted deques where elements can only be removed from one end but inserted from both ends. Deques can function as stacks or queues depending on the insertion and removal ends. The document describes algorithms for common deque operations like insert_front, insert_back, remove_front, and remove_back. It also lists applications of deques like palindrome checking and task scheduling.
![Algorithm Insert_front
step1. Start
step2. Check the queue is full or not as if (r == max-1) &&(f==0)
step3. If false update the pointer f as f= f-1
step4. Insert the element at pointer f as Q[f] = element
step5. Stop](https://image.slidesharecdn.com/dequeanditsapplications-111130111845-phpapp01/85/Deque-and-its-applications-7-320.jpg)
![Alogrithm insert_back
Step1: Start
Step2: Check the queue is full or not as if (r == max-1)
&&(f==0) if yes queue is full
Step3: If false update the pointer r as r= r+1
Step4: Insert the element at pointer r as Q[r] = element
Step5: Stop](https://image.slidesharecdn.com/dequeanditsapplications-111130111845-phpapp01/85/Deque-and-its-applications-9-320.jpg)
![Alogrithm Remove_front
Step1: Start
Step2: Check the queue is empty or not as if (f == r) if yes queue is
empty.
Step3: If false update pointer f as f = f+1 and delete element at
position f as element = Q[f]
Step4: If ( f== r) reset pointer f and r as f = r = -1
Step5: Stop](https://image.slidesharecdn.com/dequeanditsapplications-111130111845-phpapp01/85/Deque-and-its-applications-11-320.jpg)
![Alogrithm Remove_back
step1. Start
step2. Check the queue is empty or not as if (f == r) if yes queue
is empty
step3. If false delete element at position r as element = Q[r]
step4. Update pointer r as r = r-1
step5. If (f == r ) reset pointer f and r as f = r= -1
step6. Stop](https://image.slidesharecdn.com/dequeanditsapplications-111130111845-phpapp01/85/Deque-and-its-applications-13-320.jpg)
Deque and its applications
- 1. PRESENTED BY Chandramohan.R Manoranjani.K Racchana.K Rosalin Mary.S Saddam Hussain .J
- 2. Double-Ended Queue A Deque or deck is a double-ended queue. Allows elements to be added or removed on either the ends.
- 3. TYPES OF DEQUE Input restricted Deque Elements can be inserted only at one end. Elements can be removed from both the ends. Output restricted Deque Elements can be removed only at one end. Elements can be inserted from both the ends.
- 4. Deque as Stack and Queue As STACK When insertion and deletion is made at the same side. As Queue When items are inserted at one end and removed at the other end.
- 5. OPERATIONS IN DEQUE Insert element at back Insert element at front Remove element at front Remove element at back
- 6. Insert_front insert_front() is a operation used to push an element into the front of the Deque. PUSH 0 1 2 3 4 5 7 FRONT REAR 0 1 2 3 4 5 7
- 7. Algorithm Insert_front step1. Start step2. Check the queue is full or not as if (r == max-1) &&(f==0) step3. If false update the pointer f as f= f-1 step4. Insert the element at pointer f as Q[f] = element step5. Stop
- 8. Insert_back insert_back() is a operation used to push an element at the back of a Deque. 1 2 3 4 5 7 PUSH 9 FRONT REAR 1 2 3 4 5 7
- 9. Alogrithm insert_back Step1: Start Step2: Check the queue is full or not as if (r == max-1) &&(f==0) if yes queue is full Step3: If false update the pointer r as r= r+1 Step4: Insert the element at pointer r as Q[r] = element Step5: Stop
- 10. Remove_front remove_front() is a operation used to pop an element on front of the Deque. POP 1 2 3 4 5 7 FRONT REAR 2 3 4 5 7
- 11. Alogrithm Remove_front Step1: Start Step2: Check the queue is empty or not as if (f == r) if yes queue is empty. Step3: If false update pointer f as f = f+1 and delete element at position f as element = Q[f] Step4: If ( f== r) reset pointer f and r as f = r = -1 Step5: Stop
- 12. Remove_back • remove_front() is a operation used to pop an element on front of the Deque. 1 2 3 4 5 7 POP FRONT REAR 1 2 3 4 5
- 13. Alogrithm Remove_back step1. Start step2. Check the queue is empty or not as if (f == r) if yes queue is empty step3. If false delete element at position r as element = Q[r] step4. Update pointer r as r = r-1 step5. If (f == r ) reset pointer f and r as f = r= -1 step6. Stop
- 14. Empty It is used to test weather the Deque is empty or not.
- 16. APPLICATIONS OF DEQUE A-Steal job scheduling algorithm The A-Steal algorithm implements task scheduling for several processors(multiprocessor scheduling). The processor gets the first element from the deque. When one of the processor completes execution of its own threads it can steal a thread from another processor. It gets the last element from the deque of another processor and executes it.
- 17. OTHER APPLICATIONS OF DEQUE Undo-Redo operations in Software applications.
- 18. Thank You