LeetCode: Balanced Binary Tree

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
private:
    int getHeight(TreeNode *root){
        if(!root) return 0;
        return 1+max(getHeight(root->left),getHeight(root->right));
    }
public:
    bool isBalanced(TreeNode *root) {
        if(!root) return true;
        else return (isBalanced(root->left) && isBalanced(root->right) && abs(getHeight(root->left) - getHeight(root->right)) <=1);
    }
};