Algorithm and Data Structure - Queue

Algorithm and Data Structure - Queue

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  Algorithm and Data Structure AndiNurkholis, S.Kom, M.Kom Study Program of Informatics Faculty of Engineering and Computer Science SY. 2020-2021 April 19, 2021
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  2 5 Queue
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  3 What is Queue? LikeStack, Queue is a linear structure which follows a particular order in which the operations are performed. The order is First In First Out (FIFO). A good example of queue is any queue of consumers for a resource where the consumer that came first is served first.
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  4 Illustration
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  5 Queue VS Stack Thedifference between stacks and queues is in removing. In a stack we remove the item the most recently added; in a queue, we remove the item the least recently added
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  6 Queue Operations 1) Enqueue 2) Dequeue 3)Front 4) Rear
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  7 Enqueue Enqueue: Adds anitem in the stack. If the stack is full, then it is said to be an Overflow condition.
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  Steps of Enqueue Step1 − Check if the queue is full. Step 2 − If the queue is full, produce overflow error and exit. Step 3 − If the queue is not full, increment rear pointer to point the next empty space. Step 4 − Add data element to the queue location, where the rear is pointing. Step 5 − return success. 8
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  9 Enqueue Algorithm begin procedureenqueue(data) if queue is full return overflow endif rear ← rear + 1 queue[rear] ← data return true end procedure
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  Dequeue Dequeue: Removes anitem from the queue. The items are popped in the same order in which they are pushed. If the queue is empty, then it is said to be an Underflow condition. 10
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  Steps of Dequeue Step1 − Check if the queue is empty. Step 2 − If the queue is empty, produce underflow error and exit. Step 3 − If the queue is not empty, access the data where front is pointing. Step 4 − Increment front pointer to point to the next available data element. Step 5 − Return success. 11
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  Dequeue Algorithm begin proceduredequeue if queue is empty return underflow end if data = queue[front] front ← front + 1 return true end procedure 12
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  Front Front: Get thefront item from queue. 13 Front Algorithm: begin procedure front return queue[top] end procedure
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  Rear Rear: Get thelast item from queue. Rear Algorithm: begin procedure rear return queue[last] end procedure 14
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  Working of Queue Thisabstract data type​ can be implemented in C in multiple ways. One such way is by using an array. Pro of using an array: Easy to implement. Con of using an array: Static Data Structure, fixed size. 15
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  Queue Application 1. CPUscheduling, Disk Scheduling 2. When data is transferred asynchronously between two processes.The queue is used for synchronization. For example: IO Buffers, pipes, file IO, etc 3. Handling of interrupts in real-time systems. 4. Call Center phone systems use Queues to hold people calling them in order. 16
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  Thank You, Next… Searching April 19, 2021 Andi Nurkholis, S.Kom, M.Kom Study Program of Informatics Faculty of Engineering and Computer Science SY. 2020-2021