Class 10 | Implementation: Stacks and Queues

Article: Stacks and Queues

Notes on Stacks & Queues reading from CF

• Stack is the data structure of nodes which reference other nodes in the “stack”, think vertical
• Queue is similiar to stack but horizontal, and a place where things que up to be pushed onto the stack

Both models follow FIFO(first in first out) & LILO(last in last out) flow

• There are 2 key terms both flows share which are: peek and isEmpty.
  • With peek you are looking at the “first” node, so for stack it’s the top node and for queue it’s the front node to be specific
  • When you peek on either, you’re peeking at the top or front node respectively
  • isEmpty returns boolean true when the queue or stack is empty
• All the key terms take BigO O(1) since they take the same amount of time no matter how many nodes are in the stack or queue

Stack Terms

• Push	a node put into the stack

• Pop	a node removed from the stack

• Top	the node on the top of the stack

• Peek (see above)
• isEmpty (see above)

Queue Terms

• Enqueue

  a node added to the que

• Dequeue

  a node removed from que

• Front

  the first node of the que

• Rear	the last node of the que

• Peek (see above)
• isEmpty (see above)

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