Hash for Hashmap
(lib/misc/custom_hash.hpp)

• View this file on GitHub
• Last update: 2024-06-13 09:27:31+08:00
• Include: #include "lib/misc/custom_hash.hpp"
• Link: http://xorshift.di.unimi.it/splitmix64.c

Code

#pragma once
#include <chrono>

/**
 * @brief Hash for Hashmap
 */
struct custom_hash
{
  static uint64_t splitmix64(uint64_t x)
  {
    // http://xorshift.di.unimi.it/splitmix64.c
    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 =
        std::chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};

#line 2 "lib/misc/custom_hash.hpp"
#include <chrono>

/**
 * @brief Hash for Hashmap
 */
struct custom_hash
{
  static uint64_t splitmix64(uint64_t x)
  {
    // http://xorshift.di.unimi.it/splitmix64.c
    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 =
        std::chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};

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