@学委 从我的模板里截的片段...

template<> inline double read()
    {
        register double aa, bb;
        register char ch;
        register char *S = io::S, *T = io::T;
        while (ch = getc(), (ch<'0' || ch>'9'))
            ; aa = ch - '0';
        while (ch = getc(), (ch >= '0'&&ch <= '9'))
            aa = aa * 10 + ch - '0';
        if (ch == '.') {
            bb = 1;
            while (ch = getc(), ch >= '0'&&ch <= '9')
                bb *= 0.1, aa += bb*(ch - '0');
        }
        io::S = S, io::T = T;
        return aa;
    }
    double(*readf)() = read<double>;

实测还是挺快的QAQ