Renamed Datastructures -> Data Structure

Following uniform naming convention in the repo

Data Structure/AVLtree.cpp

@@ -0,0 +1,159 @@
+#include <iostream>
+#include <queue>
+
+using namespace std;
+
+typedef struct node {
+	int data;
+	int height;
+	struct node* left;
+	struct node* right;
+}node;
+
+int max(int a, int b) {
+	return a > b ? a : b;
+}
+
+// Returns a new Node
+
+node* createNode(int data) {
+	node *nn = new node();
+	nn->data = data;
+	nn->height = 0;
+	nn->left = NULL;
+	nn->right = NULL;
+	return nn;
+}
+
+// Returns height of tree
+
+int height(node *root) {
+	if(root==NULL)
+		return 0;
+	return 1 + max(height(root->left), height(root->right));
+}
+
+// Returns difference between height of left and right subtree
+
+int getBalance(node *root) {
+	return height(root->left) - height(root->right);
+}
+
+// Returns Node after Right Rotation
+
+node* rightRotate(node *root) {
+	node *t = root->left;
+	node *u = t->right;
+	t->right = root;
+	root->left = u;
+	return t;
+}
+
+// Returns Node after Left Rotation
+
+node* leftRotate(node *root) {
+	node *t = root->right;
+	node *u = t->left;
+	t->left = root;
+	root->right = u;
+	return t;
+}
+
+// Returns node with minimum value in the tree
+
+node* minValue(node* root) {
+	if(root->left==NULL)
+		return root;
+	return minValue(root->left);
+}
+
+// Balanced Insertion
+
+node* insert(node* root, int item) {
+	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;
+}
+
+// Balanced Deletion
+
+node* deleteNode(node *root, int key) {
+	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;
+}
+
+
+// LevelOrder (Breadth First Search)
+
+void levelOrder(node* root) {
+	queue<node*> q;
+	q.push(root);
+	while(!q.empty()) {
+		root = q.front();
+		cout<<root->data<<" ";
+		q.pop();
+		if(root->left)
+			q.push(root->left);
+		if(root->right)
+			q.push(root->right);
+	}
+}
+
+int main() {
+	// Testing AVL Tree
+	node *root = NULL;
+	int i;
+	for(i = 1 ; i <= 7 ; i++)
+		root = insert(root, i);
+	cout<<"LevelOrder: ";
+	levelOrder(root);
+	root = deleteNode(root, 1); // Deleting key with value 1
+	cout<<"\nLevelOrder: ";
+	levelOrder(root);
+    root = deleteNode(root, 4); // Deletin key with value 4
+	cout<<"\nLevelOrder: ";
+	levelOrder(root);
+	return 0;
+}