LeetCode-Balanced Binary Tree

Given a binary tree, determine if it is height-balanced.

For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

class Solution {
public:
    int sub(TreeNode* root){
        if(root==NULL)return 0;
        int h1=sub(root->left);
        int h2=sub(root->right);
        if(h1==-1||h2==-1)return -1;
        if(h1-h2>=-1&&h1-h2<=1){
            return max(h1,h2)+1;
        }
        else return -1;
        
    }
    bool isBalanced(TreeNode *root) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(sub(root)!=-1)return true;
        else return false;
    }
};