avltree.cpp File Reference

A simple tree implementation using nodes. More...

#include <algorithm>
#include <iostream>
#include <queue>

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Classes
class	node< Kind >

Typedefs
typedef struct node	node

Functions
node *	createNode (int data)
int	height (node *root)
int	getBalance (node *root)
node *	rightRotate (node *root)
node *	leftRotate (node *root)
node *	minValue (node *root)
node *	insert (node *root, int item)
node *	deleteNode (node *root, int key)
void	levelOrder (node *root)
int	main ()

Detailed Description

A simple tree implementation using nodes.

Todo:

update code to use C++ STL library features and OO structure

Warning

This program is a poor implementation and does not utilize any of the C++ STL features.

Function Documentation

createNode()

node* createNode

(

int

data

)

Create and return a new Node

                           {
    node *nn = new node();
    nn->data = data;
    nn->height = 0;
    nn->left = NULL;
    nn->right = NULL;
    return nn;
}

deleteNode()

node* deleteNode	(	node *	root,
		int	key
	)

Balanced Deletion

                                      {
    if (root == NULL)
        return root;
    if (key < root->data)
        root->left = deleteNode(root->left, key);
    else if (key > root->data)
        root->right = deleteNode(root->right, key);
 
    else {
        // Node to be deleted is leaf node or have only one Child
        if (!root->right) {
            node *temp = root->left;
            delete (root);
            root = NULL;
            return temp;
        } else if (!root->left) {
            node *temp = root->right;
            delete (root);
            root = NULL;
            return temp;
        }
        // Node to be deleted have both left and right subtrees
        node *temp = minValue(root->right);
        root->data = temp->data;
        root->right = deleteNode(root->right, temp->data);
    }
    // Balancing Tree after deletion
    return root;
}

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getBalance()

int getBalance

(

node *

root

)

Returns difference between height of left and right subtree

{ return height(root->left) - height(root->right); }

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height()

int height

(

node *

root

)

Returns height of tree

                       {
    if (root == NULL)
        return 0;
    return 1 + std::max(height(root->left), height(root->right));
}

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insert()

node* insert	(	node *	root,
		int	item
	)

Balanced Insertion

                                   {
    node *nn = createNode(item);
    if (root == NULL)
        return nn;
    if (item < root->data)
        root->left = insert(root->left, item);
    else
        root->right = insert(root->right, item);
    int b = getBalance(root);
    if (b > 1) {
        if (getBalance(root->left) < 0)
            root->left = leftRotate(root->left);  // Left-Right Case
        return rightRotate(root);                 // Left-Left Case
    } else if (b < -1) {
        if (getBalance(root->right) > 0)
            root->right = rightRotate(root->right);  // Right-Left Case
        return leftRotate(root);                     // Right-Right Case
    }
    return root;
}

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leftRotate()

node* leftRotate

(

node *

root

)

Returns Node after Left Rotation

                             {
    node *t = root->right;
    node *u = t->left;
    t->left = root;
    root->right = u;
    return t;
}

levelOrder()

void levelOrder

(

node *

root

)

LevelOrder (Breadth First Search)

                            {
    std::queue<node *> q;
    q.push(root);
    while (!q.empty()) {
        root = q.front();
        std::cout << root->data << " ";
        q.pop();
        if (root->left)
            q.push(root->left);
        if (root->right)
            q.push(root->right);
    }
}

main()

int main

(

)

Main function

           {
    // Testing AVL Tree
    node *root = NULL;
    int i;
    for (i = 1; i <= 7; i++) root = insert(root, i);
    std::cout << "LevelOrder: ";
    levelOrder(root);
    root = deleteNode(root, 1);  // Deleting key with value 1
    std::cout << "\nLevelOrder: ";
    levelOrder(root);
    root = deleteNode(root, 4);  // Deletin key with value 4
    std::cout << "\nLevelOrder: ";
    levelOrder(root);
    return 0;
}

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minValue()

node* minValue

(

node *

root

)

Returns node with minimum value in the tree

                           {
    if (root->left == NULL)
        return root;
    return minValue(root->left);
}

rightRotate()

node* rightRotate

(

node *

root

)

Returns Node after Right Rotation

                              {
    node *t = root->left;
    node *u = t->right;
    t->right = root;
    root->left = u;
    return t;
}