랜덤 시드를 활용한 해시 + 해시맵

random_hasher.cpp

#include<bits/stdc++.h>
using namespace std;

struct SingletonRand
{
    size_t value;
    SingletonRand()
    {
        auto curTime = chrono::system_clock::now(); auto duration = curTime.time_since_epoch();
        auto timer = chrono::duration_cast<chrono::nanoseconds>(duration).count();
        mt19937_64 mtRand(timer);
        value=mtRand();
    }
};

SingletonRand Seed = SingletonRand();

template <class T>
struct RandHasher
{
    size_t operator()(T const& rh) const
    {
        return hash<size_t>()(Seed.value)^hash<T>()(rh);
    }
};

int main()
{
    unordered_map<string,int,RandHasher<string>> umap;
    umap["hello"] = 12345;
    umap["world"] = 67890;
    cout << umap["hello"] << " " << umap["world"] << endl;
    cout<< RandHasher<string>()("hello") << " " << RandHasher<string>()("world") << endl;
}