没转double

45pts：

inline int S(int a, int b, int c)
{
    double t = (a + b + c) / 2;
    return 100 * sqrt(t * (t - a) * (t - b) * (t - c));
}

100pts：

inline int S(int a, int b, int c)
{
    double t = (a + b + c) / 2.0;
    return 100 * sqrt(t * (t - a) * (t - b) * (t - c));
}