Added AVL Tree Implementation

Author: vshalprashr

data-structures/avl.cpp

@@ -0,0 +1,175 @@
+#include <iostream>
+#include <queue>
+using namespace std;
+
+struct node
+{
+	int data, height;
+	node *left, *right;
+};
+
+class avl
+{
+	node* root=NULL;
+public:
+	int height(node* root){
+		if(root)
+			return root->height;
+		return 0;
+	}
+	node* rotateLeft(node* root){
+		node* newroot = root->right;
+		root->right = newroot->left;
+		newroot->left = root;
+		return newroot;
+	}
+	node* rotateRight(node* root){
+		node* newroot = root->left;
+		root->left = newroot->right;
+		newroot->right = root;
+		return newroot;
+	}
+	void insert(int x){
+		this->root = insert(this->root, x);
+	}
+	node* insert(node* root, int x){
+		if(root==NULL){
+			root = new node;
+			root->data = x;
+			root->height = 1;
+			root->left = NULL;
+			root->right = NULL;
+			return root;
+		}
+		if(x < root->data)
+			root->left = insert(root->left,x);
+		else if(x > root->data)
+			root->right = insert(root->right,x);
+		else
+			return root;
+
+		int lh = height(root->left), rh = height(root->right);
+		root->height = 1 + max(lh,rh);
+
+		lh -= rh;
+		if(lh>1){
+			if(x > root->left->data)
+				root->left = rotateLeft(root->left);
+			return rotateRight(root);
+		}
+		else if(lh<-1){
+			if(x < root->right->data)
+				root->right = rotateRight(root->right);
+			return rotateLeft(root);
+		}
+		return root;
+	}
+	int minValue(node* root){
+		while(root->left)
+			root = root->left;
+		return root->data;
+	}
+	void remove(int x){
+		this->root = remove(this->root, x);
+	}
+	node* remove(node* root, int x){
+		if(root == NULL)
+			return NULL;
+		if(x < root->data)
+			root->left = remove(root->left, x);
+		else if(x > root->data)
+			root->right = remove(root->right, x);
+		else{
+			if(root->left == NULL && root->right == NULL){
+				delete root;
+				return NULL;
+			}
+			else if(root->right == NULL){
+				node* temp = root;
+				root = root->left;
+				delete temp;
+				return root;
+			}
+			else if(root->left == NULL){
+				node* temp = root;
+				root = root->right;
+				delete temp;
+				return root;
+			}
+			else{
+				root->data = minValue(root->right);
+				root->right = remove(root->right, root->data);
+			}
+		}
+
+		int lh = height(root->left), rh = height(root->right);
+		root->height = 1 + max(lh,rh);
+
+		lh -= rh;
+		if(lh>1){
+			if(x > root->left->data)
+				root->left = rotateLeft(root->left);
+			return rotateRight(root);
+		}
+		else if(lh<-1){
+			if(x < root->right->data)
+				root->right = rotateRight(root->right);
+			return rotateLeft(root);
+		}
+		return root;
+	}
+	void printLevel(){
+		printLevel(this->root);
+	}
+	void printLevel(node* root){
+		if(root){
+			queue<node*> q;
+			q.push(root);
+			q.push(NULL);
+			node* temp;
+			while(!q.empty()){
+				temp = q.front();
+				q.pop();
+				if(temp){
+					cout << temp->data << " ";
+					if(temp->left)
+						q.push(temp->left);
+					if(temp->right)
+						q.push(temp->right);
+				}
+				else if(q.front()){
+					cout << endl;
+					q.push(NULL);
+				}
+			}
+		}
+	}
+	void print(){
+		print(this->root);
+	}
+	void print(node* root){
+		if(root){
+			print(root->left);
+			cout << root->data << " ";
+			print(root->right);
+		}
+	}
+};
+
+int main()
+{
+	avl a;
+	a.insert(5);
+	a.insert(6);
+	a.insert(7);
+	a.insert(8);
+	a.insert(9);
+	a.insert(4);
+	a.printLevel();
+	a.remove(7);
+	a.remove(5);
+	cout << endl;
+	a.printLevel();
+	
+	return 0;
+}