Node *left;
Node *right;
Node *parent;
int height; // add this one


int max(int a, int b)
{
    return (a > b)? a : b;
}

Node * minValueNode(Node* node)
{
    Node* current = node;

    while (current->left != NULL)
        current = current->left;

    return current;
}

int getBalance(Node *N)
{
    if (N == NULL)
        return 0;
    return height(N->left) - height(N->right);
}

Node *leftRotate(Node *x)
{
    Node *y = x->right;
    Node *T2 = y->left;

    y->left = x;
    x->right = T2;

    x->height = max(height(x->left), height(x->right)) + 1;
    y->height = max(height(y->left), height(y->right)) + 1;

    return y;
}

Node *rightRotate(Node *y)
{
    Node *x = y->left;
    Node *T2 = x->right;

    x->right = y;
    y->left = T2;

    y->height = max(height(y->left),
                    height(y->right)) + 1;
    x->height = max(height(x->left),
                    height(x->right)) + 1;

    return x;
}

Node* deleteNodes(Node* root, int key)
{
    if (root == NULL)
        return root;

    if ( key < root->key )
        root->left = deleteNodes(root->left, key);
    else if( key > root->key )
        root->right = deleteNodes(root->right, key);
    else
    {
        if( (root->left == NULL) ||
            (root->right == NULL) )
        {
            Node *temp = root->left ? root->left : root->right;

            if (temp == NULL)
            {
                temp = root;
                root = NULL;
            }
            else
            *root = *temp;
            free(temp);
        }
        else
        {
            Node* temp = minValueNode(root->right);

            root->key = temp->key;

            root->right = deleteNodes(root->right, temp->key);
        }
    }

    if (root == NULL)
    return root;

    root->height = 1 + max(height(root->left), height(root->right));

    int balance = getBalance(root);

    if (balance > 1 && getBalance(root->left) >= 0)
        return rightRotate(root);

    if (balance > 1 && getBalance(root->left) < 0)
    {
        root->left = leftRotate(root->left);
        return rightRotate(root);
    }

    if (balance < -1 && getBalance(root->right) <= 0)
        return leftRotate(root);

    if (balance < -1 && getBalance(root->right) > 0)
    {
        root->right = rightRotate(root->right);
        return leftRotate(root);
    }

    return root;
}