安全的雜湊

安全的雜湊

程式碼如下

const int maxn = 2e5 + 5;
struct custom_hash 
{
	static uint64_t splitmix64(uint64_t x) 
    {
		x ^= x << 13;
		x ^= x >> 7;
		x ^= x << 17;
		return x; 
	}
	size_t operator () (uint64_t x) const 
    {
		static const uint64_t FIXED_RANDOM = std::chrono::steady_clock::now().time_since_epoch().count(); // 時間戳
		return splitmix64(x + FIXED_RANDOM);
	}
};
std::unordered_map<uint64_t, int, custom_hash> mp;