sword to offer 039

class  {
private:
    int GetHeight(TreeNode* root) {
        if(root == nullptr) {
            return 0;
        }
        int leftHeight = GetHeight(root->left);
        int rightHeight = GetHeight(root->right);
        return max(leftHeight, rightHeight) + 1;
    }
public:
    bool IsBalanced_Solution(TreeNode* pRoot) {
        if(pRoot == nullptr) {
            return true;
        }
        int leftHeight = GetHeight(pRoot->left);
        int rightHeight = GetHeight(pRoot->right);
        if(abs(leftHeight - rightHeight) > 1) {
            return false;
        }
        return IsBalanced_Solution(pRoot->left) && IsBalanced_Solution(pRoot->right);
    }
};