C++程序：判断从a到b连续数字和是否为幸运数

```cpp #include <iostream> using namespace std; int main() { int a, b; cin >> a >> b; int sum = (a + b) * (b - a + 1) / 2; if (sum % 7 == 0) { cout << "幸运"; } else { cout << sum; } return 0; } ``` ######[AI问答 | 99点数解答 | 2025-12-12 19:25:57]