Stacks and QueuesTruong Tuan Anh

CSE-HCMUT

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Outline

Basic conceptsStacksQueues

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Stacks

A stack of elements of type T is a finite sequenceof elements of T, in which all insertions and deletions are restricted to one end, called the topStack is a Last In - First Out (LIFO) data structure.LIFO: The last item put on the stack is the first item that can be taken off

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Basic Operations of Stacks

Construct a stack, leaving it emptyPush an element: put a new element on to the top of the stackPop an element: remove the top element from the top of the stackTop an element: retrieve the top element

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Push an Element

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Push an Element: Overflow

Nothing changed in the stack

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Pop an Element

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Pop an Element: Underflow

Nothing changed in the stack

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Implementation of Stacks

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Using Linked List

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Using Linked List

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Using Linked List: C++

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Create an empty Linked Stack

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Push Data into a Linked Stack

1. Allocate memory for the new node and set up data

2. Update pointers:1. Point the new node to the top node (before adding the

new node)2. Point top to the new node

3. Update count

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Push Data into a Linked Stack

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Push Data into a Linked Stack: C++

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Pop

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Pop Linked Stack

1. dltPtr holds the element on the top of the stack2. top points to the next element3. Recycle dltPtr. Decrease count by 1

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Pop Linked Stack: C++

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Other Functions

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Destroy a Linked Stack

Release all nodes in the stack→ save memory

How?

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Destroy a Linked Stack

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Print out a Linked Stack

Print all nodes’ data

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Using a Linked Stack

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Read More

Array-based stack implementation

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Queues

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Queues

A queue of elements of type T is a finite sequence of elements of T, in which data can only be inserted at one end called the rear, and deleted from the other end called the frontQueue is a First In - First Out (FIFO) data structureFIFO: The first item stored in the queue is the first item that can be taken out

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Basic Operations of Queues

Construct a queue, leaving it emptyEnqueue: put a new element into the rear of the queueDequeue: remove the first element from the front of the queueQueue Front: retrieve the front elementQueue Rear: retrieve the rear element

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Enqueue

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Dequeue

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Implementation of Queues

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Using Linked List

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Using Linked List

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Using Linked List: C++

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Creating Queue

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Creating Queue

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Enqueue: Insert into an Empty Queue

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Enqueue: Insert into a Queue

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Enqueue: C++

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Dequeue: Delete an Item in a Queue Having only one Item

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Dequeue: Delete an Item in a Queue

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Dequeue: C++

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Queue: Other Functions

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Destroy a Linked Queue

Release all nodes in the Queue→ save memory

How?

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Destroy a Linked Queue

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Print out a Linked Queue

Print all nodes’ data

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Using a Linked Queue

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Read More

Array-based queue implementation

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Takeaways

Basic conceptsStacksQueues