单选题库

TreeNode* search(TreeNode* root, int target) {
    if (root == NULL || root->val == target) {
        return root;
    }
    if (_____________) {
        return search(root->left, target);
    } else {
        return search(root->right, target);
    }
}

class Circle {
private:
    double radius;
public:
    Circle(double r) : radius(r) {}
    double getArea() {
        return 3.14 * radius * radius;
    }
};