int height(TreeNode * root){
        if(root!=nullptr)
            return max(height(root->right),height(root->left))+1;
        return 0;
    }

    bool isBalanced(TreeNode* root) {
        if(root!=nullptr)
            return abs(height(root->left)-height(root->right))<2
                &&isBalanced(root->right)
                &&isBalanced(root->left);
        return true;

    }

​