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哈希表重写哈希函数

模版
C++
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struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        x += 0x9e3779b97f4a7c15;
        x = (x ^ x >> 30) * 0xbf58476d1ce4e5b9;
        x = (x ^ x >> 27) * 0x94d049bb133111eb;
        return x ^ x >> 31;
    }
    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};
unordered_map<int, int, custom_hash> safe_map;
C++
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struct pair_hash {
    template<class T1, class T2>
    size_t operator() (const pair<T1, T2>& pair) const {
        return hash<T1>()(pair.first) ^ hash<T2>()(pair.second);
    }
};
unordered_map<pair<int, int>, int, pair_hash> safe_map;