C++ Two Function 4 line Solution

```
class Solution {
public:
int countChild(TreeNode* node) {
if (node == nullptr) return 0;
return node->val + countChild(node->left) + countChild(node->right);
}
int findTilt(TreeNode* root) {
if (root == nullptr) return 0;
return abs(countChild(root->left) - countChild(root->right)) + findTilt(root->left) + findTilt(root->right);
}
};
```