手写HASH模版

手写 \(HASH\)

可以是 \(ump\) 能够用 \(pair\)。

struct Hash {
	static uint64_t splitmix64(uint64_t x) {
		x += 0x9e3779b97f4a7c15;
		x = (x ^ x >> 30) * 0xbf58476d1ce4e5b9;
		x = (x ^ x >> 27) * 0x94d049bb133111eb;
		return x ^ x >> 31;
	}
	
	static size_t get(const uint64_t x) {
		static const ui64 FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
		return splitmix64(x + FIXED_RANDOM);
	}
	
	template <typename T>
	size_t operator() (T x) const {
		return get(std::hash<T>()(x));
	}
	
	template <typename F, typename S>
	size_t operator() (pair<F, S> p) const {
		return get(std::hash<F>()(p.first)) ^ std::hash<S>()(p.second);
	}
};

unordered_map<PI, i64, Hash> mp;