C++ program to implement AVL Tree Operations using Linked List

By | 08.01.2017
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AVL Tree Operations using Linked List

Write a C++ program to implement AVL Tree Operations using Linked List. Here’s simple C++ program to implement AVL Tree Operations using Linked List in C++ Programming Language.

What is Linked List ?

Linked list is a linear data structure that contains sequence of elements such that each element links to its next element in the sequence. Each link contains a connection to another link.

Following are the important terms to understand the concept of Linked List.

  • Link − Each link of a linked list can store a data called an element.
  • Next − Each link of a linked list contains a link to the next link called Next.

Each element in a linked list is called as “Node”. Each node consists of its own data and the address of the next node and forms a chain. Linked Lists are used to create trees and graphs.

Below is the source code for C++ program to implement AVL Tree Operations using Linked List which is successfully compiled and run on Windows System to produce desired output as shown below :

SOURCE CODE : :

/*  C++ program to implement AVL Tree Operations using Linked List  */

#include <iostream>
#include <stdlib.h>

using namespace std;

#define FALSE 0
#define TRUE 1
struct AVLNode
{
        int data ;
        int balfact ;
        AVLNode *left ;
        AVLNode *right ;
} ;
 
class avltree
{
        private :
                AVLNode *root ;
        public :
                avltree( ) ;
                AVLNode*  insert ( int data, int *h ) ;
                static AVLNode* buildtree ( AVLNode *root, int data, int *h ) ;
                void display( AVLNode *root ) ;
                AVLNode* deldata ( AVLNode* root, int data, int *h ) ;
                static AVLNode* del ( AVLNode *node, AVLNode* root, int *h ) ;
                static AVLNode* balright ( AVLNode *root, int *h ) ;
                static AVLNode* balleft ( AVLNode* root, int *h ) ;
                void setroot ( AVLNode *avl ) ;
                ~avltree( ) ;
                static void deltree ( AVLNode *root ) ;
} ;
avltree :: avltree( )
{
        root = NULL ;
}
AVLNode* avltree :: insert ( int data, int *h )
{
        root = buildtree ( root, data, h ) ;
        return root ;
}
AVLNode* avltree :: buildtree ( AVLNode *root, int data, int *h )
{
        AVLNode *node1, *node2 ;
 
        if ( root == NULL )
        {
                root = new AVLNode ;
                root -> data = data ;
                root -> left = NULL ;
                root -> right = NULL ;
                root -> balfact = 0 ;
                *h = TRUE ;
                return ( root ) ;
        }
        if ( data < root -> data )
        {
                root -> left = buildtree ( root -> left, data, h ) ;
 
                // If left subtree is higher
                if ( *h )
                {
                        switch ( root -> balfact )
                        {
                                case 1 :
                                        node1 = root -> left ;
                                        if ( node1 -> balfact == 1 )
                                        {
                                                cout << "\nRight rotation." ;
                                                root -> left = node1 -> right ;
                                                node1 -> right = root ;
                                                root -> balfact = 0 ;
                                                root = node1 ;
                                        }
                                        else
                                        {
                                                cout << "\nDouble rotation, left then right." ;
                                                node2 = node1 -> right ;
                                                node1 -> right = node2 -> left ;
                                                node2 -> left = node1 ;
                                                root -> left = node2 -> right ;
                                                node2 -> right = root ;
                                                if ( node2 -> balfact == 1 )
                                                        root -> balfact = -1 ;
                                                else
                                                        root -> balfact = 0 ;
                                                if ( node2 -> balfact == -1 )
                                                        node1 -> balfact = 1 ;
                                                else
                                                        node1 -> balfact = 0 ;
                                                root = node2 ;
                                        }
                                        root -> balfact = 0 ;
                                        *h = FALSE ;
                                        break ;
 
                                case 0 :
                                        root -> balfact = 1 ;
                                        break ;
                                case -1 :
                                        root -> balfact = 0 ;
                                        *h = FALSE ;
                        }
                }
        }
 
        if ( data > root -> data )
        {
                root -> right = buildtree ( root -> right, data, h ) ;
 
                if ( *h )
                {
                        switch ( root -> balfact )
                        {
                                case 1 :
                                        root -> balfact = 0 ;
                                        *h = FALSE ;
                                        break ;
                                case 0 :
                                        root -> balfact = -1 ;
                                        break ;
                                case -1 :
                                        node1 = root -> right ;
                                        if ( node1 -> balfact == -1 )
                                        {
                                                cout << "\nLeft rotation." ;
                                                root -> right = node1 -> left ;
                                                node1 -> left = root ;
                                                root -> balfact = 0 ;
                                                root = node1 ;
                                        }
                                        else
                                        {
                                                cout << "\nDouble rotation, right then left." ;
                                                node2 = node1 -> left ;
                                                node1 -> left = node2 -> right ;
                                                node2 -> right = node1 ;
                                                root -> right = node2 -> left ;
                                                node2 -> left = root ;
                                                if ( node2 -> balfact == -1 )
                                                        root -> balfact = 1 ;
                                                else
                                                        root -> balfact = 0 ;
                                                if ( node2 -> balfact == 1 )
                                                        node1 -> balfact = -1 ;
                                                else
                                                        node1 -> balfact = 0 ;
                                                root = node2 ;
                                        }
                                        root -> balfact = 0 ;
                                        *h = FALSE ;
                        }
                }
        }
        return ( root ) ;
}
void avltree :: display ( AVLNode* root )
{
        if ( root != NULL )
        {
                display ( root -> left ) ;
                cout << root -> data << "\t" ;
                display ( root -> right ) ;
        }
}
AVLNode* avltree :: deldata ( AVLNode *root, int data, int *h )
{
        AVLNode *node ;
        if ( root -> data == 13 )
                cout << root -> data ;
        if ( root == NULL )
        {
                cout << "\nNo such data." ;
                return ( root ) ;
        }
        else
        {
                if ( data < root -> data )
                {
                        root -> left = deldata ( root -> left, data, h ) ;
                        if ( *h )
                                root = balright ( root, h ) ;
                }
                else
                {
                        if ( data > root -> data )
                        {
                                root -> right = deldata ( root -> right, data, h ) ;
                                if ( *h )
                                        root = balleft ( root, h ) ;
                        }
                        else
                        {
                                node = root ;
                                if ( node -> right == NULL )
                                {
                                        root = node -> left ;
                                        *h = TRUE ;
                                        delete ( node ) ;
                                }
                                else
                                {
                                        if ( node -> left == NULL )
                                        {
                                                root = node -> right ;
                                                *h = TRUE ;
                                                delete ( node ) ;
                                        }
                                        else
                                        {
                                                node -> right = del ( node -> right, node, h ) ;
                                                if ( *h )
                                                        root = balleft ( root, h ) ;
                                        }
                                }
                        }
                }
        }
        return ( root ) ;
}
AVLNode* avltree :: del ( AVLNode *succ, AVLNode *node, int *h )
{
        AVLNode *temp = succ ;
 
        if ( succ -> left != NULL )
        {
                succ -> left = del ( succ -> left, node, h ) ;
                if ( *h )
                        succ = balright ( succ, h ) ;
        }
        else
        {
                temp = succ ;
                node -> data = succ -> data ;
                succ = succ -> right ;
                delete ( temp ) ;
                *h = TRUE ;
        }
        return ( succ ) ;
}
AVLNode* avltree :: balright ( AVLNode *root, int *h )
{
        AVLNode *temp1, *temp2 ;
        switch ( root -> balfact )
        {
                case 1 :
                        root -> balfact = 0 ;
                        break ;
                case 0 :
                        root -> balfact = -1 ;
                        *h  = FALSE ;
                        break ;
                case -1 :
                        temp1 = root -> right ;
                        if ( temp1 -> balfact <= 0 )
                        {
                                cout << "\nLeft rotation." ;
                                root -> right = temp1 -> left ;
                                temp1 -> left = root ;
                                if ( temp1 -> balfact == 0 )
                                {
                                        root -> balfact = -1 ;
                                        temp1 -> balfact = 1 ;
                                        *h = FALSE ;
                                }
                                else
                                {
                                        root -> balfact = temp1 -> balfact = 0 ;
                                }
                                root = temp1 ;
                        }
                        else
                        {
                                cout << "\nDouble rotation, right then left." ;
                                temp2 = temp1 -> left ;
                                temp1 -> left = temp2 -> right ;
                                temp2 -> right = temp1 ;
                                root -> right = temp2 -> left ;
                                temp2 -> left = root ;
                                if ( temp2 -> balfact == -1 )
                                        root -> balfact = 1 ;
                                else
                                        root -> balfact = 0 ;
                                if ( temp2 -> balfact == 1 )
                                        temp1 -> balfact = -1 ;
                                else
                                        temp1 -> balfact = 0 ;
                                root = temp2 ;
                                temp2 -> balfact = 0 ;
                        }
        }
        return ( root ) ;
}
AVLNode* avltree :: balleft ( AVLNode *root, int *h )
{
        AVLNode *temp1, *temp2 ;
        switch ( root -> balfact )
        {
                case -1 :
                        root -> balfact = 0 ;
                        break ;
 
                case 0 :
                        root -> balfact = 1 ;
                        *h = FALSE ;
                        break ;
 
                case 1 :
                        temp1 = root -> left ;
                        if ( temp1 -> balfact >= 0 )
                        {
                                cout << "\nRight rotation." ;
                                root -> left = temp1 -> right ;
                                temp1 -> right = root ;
 
                                if ( temp1 -> balfact == 0 )
                                {
                                        root -> balfact = 1 ;
                                        temp1 -> balfact = -1 ;
                                        *h = FALSE ;
                                }
                                else
                                {
                                        root -> balfact = temp1 -> balfact = 0 ;
                                }
                                root = temp1 ;
                        }
                        else
                        {
                                cout << "\nDouble rotation, left then right." ;
                                temp2 = temp1 -> right ;
                                temp1 -> right = temp2 -> left ;
                                temp2 -> left = temp1 ;
                                root -> left = temp2 -> right ;
                                temp2 -> right = root ;
                                if ( temp2 -> balfact == 1 )
                                        root -> balfact = -1 ;
                                else
                                        root -> balfact = 0 ;
                                if ( temp2-> balfact == -1 )
                                        temp1 -> balfact = 1 ;
                                else
                                        temp1 -> balfact = 0 ;
                                root = temp2 ;
                                temp2 -> balfact = 0 ;
                        }
        }
        return ( root ) ;
}
void avltree :: setroot ( AVLNode *avl )
{
        root = avl ;
}
avltree :: ~avltree( )
{
        deltree ( root ) ;
}
 
 
void avltree :: deltree ( AVLNode *root )
{
        if ( root != NULL )
        {
                deltree ( root -> left ) ;
                deltree ( root -> right ) ;
        }
        delete ( root ) ;
}
int main( )
{
        avltree at ;
        AVLNode *avl = NULL ;
        int h ;
        avl = at.insert ( 20, &h ) ;
        at.setroot ( avl ) ;
        avl = at.insert ( 6, &h ) ;
        at.setroot ( avl ) ;
        avl = at.insert ( 29, &h ) ;
        at.setroot ( avl ) ;
        avl = at.insert ( 5, &h ) ;
        at.setroot ( avl ) ;
        avl = at.insert ( 12, &h ) ;
        at.setroot ( avl ) ;
        avl = at.insert ( 25, &h ) ;
        at.setroot ( avl ) ;
        avl = at.insert ( 32, &h ) ;
        at.setroot ( avl ) ;
        avl = at.insert ( 10, &h ) ;
        at.setroot ( avl ) ;
        avl = at.insert ( 15, &h ) ;
        at.setroot ( avl ) ;
        avl = at.insert ( 27, &h ) ;
        at.setroot ( avl ) ;
        avl = at.insert ( 13, &h ) ;
        at.setroot ( avl ) ;
        cout << endl << "AVL tree:\n" ;
        at.display ( avl ) ;
        avl = at.deldata ( avl, 20, &h ) ;
        at.setroot ( avl ) ;
        avl = at.deldata ( avl, 12, &h ) ;
        at.setroot ( avl ) ;
        cout << endl << "AVL tree after deletion of a node:\n" ;
        at.display ( avl ) ;
        return 0;
}

OUTPUT : :

/*  C++ program to implement AVL Tree Operations using Linked List  */

Left rotation.
AVL tree:
5       6       10      12      13      15      20      25      27      29      32      

AVL tree after deletion of a node:
5       6       10      13      15      25      27      29      32       

Exit code: 0

Above is the source code and output for C++ program to implement AVL Tree Operations using Linked List which is successfully compiled and run on Windows System to produce desired output.

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