程序代码：

unsigned std_gcd( unsigned a, unsigned b )
{
    for( ; b!=0; )
    {
        unsigned t = a;
        a = b;
        b = t%b;
    }
    return a;
}
unsigned std_lcm( unsigned a, unsigned b )
{
    return (a==0&&b==0) ? 0 : a/std_gcd(a,b)*b;
}