Software Engineer Study Guide — Stack vs. Queue

Marika Lam

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Oct 27, 2020

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Stack

• LIFO (Last in First out)
• Same end is used to insert and delete elements
• 1 pointer used
• Operations: Push and Pop
• Check empty condition: Top == -1
• Check full condition: Top == Max-1
• No variants
• Implementation is simpler than queue

Queue

• FIFO (First in First out)
• One end is used for insertion and the other end is used for deletion of elements
• 2 pointers used (in simple queue case)
• Operations: Enqueue and dequeue
• Check empty condition: Front == -1 || Front == Rear+1
• Check full condition: Rear == Max-1
• It has variants like circular queue, priority queue and doubly ended queue
• Implementation is comparatively more complex than stack