Data Structures and Applications

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# Data Structures and Applications - PowerPoint PPT Presentation

Data Structures and Applications. Hao Jiang Computer Science Department Boston College. Linked List. head. 1. 2. 3. 4. null. … Node head; Node v1 = new Node(1); Node v2 = new Node(2); Node v3 = new Node(3); Node v4 = new Node(4); head = v1; v1.next = v2; v2.next = v3;

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### Data Structures and Applications

Hao Jiang

Computer Science Department

Boston College

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null

Node v1 = new Node(1);

Node v2 = new Node(2);

Node v3 = new Node(3);

Node v4 = new Node(4);

v1.next = v2;

v2.next = v3;

v3.next = v4; v4.next = null;

class Node {

public int d;

public Node next;

public Node(int d)

{

this.d = d;

next = null;

}

}

Some Properties

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null

A list is dynamic: the length of a list is determined in the runtime.

Some operations such as insertion and deletion are cheaper

than the data structure array.

Insert

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100

Insert a new node at position 1.

Insert in the Front

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100

Insert a new node at position 0.

Insert at the End

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null

Insert a new node at the end.

Delete

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Delete a new node at position 1.

Delete from the Front

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Delete a node at position 0.

Delete the Last Node

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Delete the last node in the list.

A List of Objects

obj1

obj2

obj3

obj4

null

class Node {

public Object d;

public Node next;

public Node(Object d)

{

this.d = d;

next = null;

}

}

A More Accurate Illustration

obj1

obj2

obj3

obj4

null

A list of objects.

List Class

public class List {

public List() { head = null; }

public boolean isEmpty() { return (head == null); }

public int length(Node h) {

if (h == null) return 0;

return 1 + length(h.next);

}

public int length() { return length(head); }

public void append() {…}

public void insert(int n, Object d) {…}

public Object delete(int n) {…}

public void print() {…}

}

Queue
• A queue is a first-in-first-out linear data structure.
• It supports two operations:
• void enQueue(Object d)
• Object deQueue()

Data

Out

Data

In

Stack
• A stack is a first-in-last-out linear data structure.
• It supports two operations:
• void push(Object d)
• Object pop()

top of the stack

bottom of the stack

Queue based on List

public class Queue {

private List list;

public Queue() {

list = new List();

}

public void enQueue(Object d) {

list.append(d);

}

public Object deQueue() {

list.delete(0);

return t.d;

}

}

Stack based on List

public class Stack {

private List list;

public Stack() {

list = new List();

}

public void push(Object d) {

list.insert(0, d);

}

public Object pop() {

list.delete(0);

return t.d;

}

}

Simulation
• Application of the Queue

Gas Station

car1

car2

car3

car4

Top of the line

End of the line

How long does everyone have to wait?

How long can the line be?

Language Parser
• We can use stacks to make language parsers.
• ( ( 1 + 2 ) / 3 ) = ?

2

1

+

3

)

( (

1 + 2

3

3

/

1

The result is

1.

)

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