首先保证a与b不相等

template <typename T, T M = 0>
inline bool AheadOf(T a, T b) {static_assert(std::is_unsigned<T>::value,"Type must be an unsigned integer.");return a != b && AheadOrAt<T, M>(a, b);
}

template <typename T, T M>
inline typename std::enable_if<(M == 0), bool>::type AheadOrAt(T a, T b) {static_assert(std::is_unsigned<T>::value,"Type must be an unsigned integer.");//std::numeric_limits<T>::max()//取出当前类型的最大值66535 2的16次方//maxDist == 32768 (32767 + 1)const T maxDist = std::nu