Chapter 16

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Chapter 16 Data Structures and Recursion
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Data Structures

• Built-in
• Array
• struct
• User developed
• linked list
• stack
• queue
• tree

Lesson 16.1
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Programmer-defined Linked List Class

• Data members (could be different types) stored in
  (usually) contiguous block of memory
• One of the data members is a pointer variable
• Address stored points to the next object
• Data member that has address creates link between
  objects
• Each object referred to as a node

Lesson 16.1
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Linked List Representation
Lesson 16.1
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Actions on Linked List

• Must go node to node from head node
• Can delete node by making address that points to
  one to be deleted to next object
• Can insert node by changing address stored in
  pointer variable for node preceding location of
  insertion
• Can move node from one location to another
• Must keep track of current node and head node

Lesson 16.1
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Linked List Classes

• Use two classes to create linked list
• Node class
• Holds only the data
• All data members public because no function
  members
• Second used to manipulate nodes
• One variable holds address of first object in
  list
• Another variable holds current node address

Lesson 16.1
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Node Class

• General form

class Node public
type member1 type member2
Node
next_node
Lesson 16.1
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Second Class
class Llist private
Node head Node current
public void make_list ( )
void show_list ( )

• Used to manipulate the nodes
• Data only pointer variables used to hold
  addresses

Lesson 16.1
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Stack

• Data structure created using linked list model
• With stack can perform only two fundamental
  operations
• Push
• Insert node immediately after the head
• Pop
• Retrieve and delete node immediately after head
• Only work with nodes at top

Lesson 16.2
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Stack Classes

• Two classes create stack
• One class holds only data
• Same form as linked list
• one member must be pointer variable
• Second class used to manipulate nodes
• Data only pointer variables used to hold
  addresses of nodes
• Nodes of interest for stack are head and tail
• Function members initialize, push and pop items

Lesson 16.2
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Stack Class
class Stack private
Node head Node tail
public Stack ( )
void push (int) int pop
( )
Lesson 16.2
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Stack Classes

• Create empty stack by initializing a head and
  tail node
• Allow finding top and bottom of stack
• Should not pop from an empty stack
• LIFO
• Last In First Out
• Last node pushed is first node popped off

Lesson 16.2
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Queue Class

• Can create with linked list form
• Must have a head and tail node
• FIFO
• First node inserted into queue is first node
  removed
• Nodes are inserted at tail of queue and removed
  from head of queue

Lesson 16.3
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Queue Class
class Queue private
Node head Node tail
public Queue ( )
void insert (int)
int remov ( )
Class Node public type
member Node next_node
Lesson 16.3
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Types of Queues

• Dequeue - "double-ended queue"
• Nodes can be inserted at either end and removed
  from either end
• Output restricted dequeue
• Insertion allowed at both ends but removal
  allowed at only one end
• Input restricted dequeue
• Removal allowed at both ends, insertion allowed
  at only one end
• Priority queue
• Priority for each node highest priority
  processed first

Lesson 16.3
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Binary Tree

• Tree is particular type of graph
• Binary tree is particular type of tree
• Graph is data structure that includes nodes
• each node can have more than one pointer

Linked List Graph
Lesson 16.4
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Graph Terminology

• Nodes can also be called vertices or points
• Connections between nodes called edges or arcs
• Two nodes considered adjacent of neighbors if
  edge connects them
• Path between one node and another indicated by
  list of connect nodes between two
• Simple path is path with no repeated nodes

Lesson 16.4
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Graphs

• Weighted graph
• Assign length or cost of each edge
• Tree
• graph with characteristic that there is only one
  path between any two nodes
• Rooted tree
• Tree with one node specified to be root
• Root traditionally shown at top of diagram
• Binary tree
• Tree in which no node has more than two children

Lesson 16.4
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Tree Class
class Tree_node public
type member Tree_node
left_child Tree_node
right_child

• Similar to linked list and stack classes
• Two classes
• One class holds content of nodes
• Second class manipulates the nodes

Lesson 16.4
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Recursion

• Within function body there is call to function
  with identical name and signature
• Basic action which is repeated until it reaches
  the final iteration of the basic action

Lesson 16.5
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Summary
Learned how to

• Create a linked list
• Create a stack
• Create a queue
• Create a binary tree
• Identify recursive functions