1.4 KiB
1.4 KiB
robin_hood::unordered_map — Fast Hash Map for C++
robin_hood::unordered_map is a high-performance hash table implementation designed as a faster alternative to std::unordered_map, with better cache locality and reduced memory overhead.
Key Features
- Faster lookups and insertions compared to
std::unordered_map - Robin Hood hashing: minimizes probe length differences to keep performance stable
- Header-only: easy to integrate
- Memory efficient: lower memory usage due to compact internal representation
- Supports custom hash and equality functions
Installation
Include the header file in your project:
#include "robin_hood.h"
You can get the header from:
GitHub: https://github.com/martinus/robin-hood-hashing
Benchmarks
Compile and run this program to see the performance difference; you will need to both robin_hood_test.cpp and robin_hood.h.
The program performs 2 millions times of insert and lookup on an std::unordered_map container; and then performs 2 million times of insert and lookup on a robin_hood::unordered_map container. As can be seen, the robin hood test runs much faster.
$g++ -o robin_hood_test robin_hood_test.cpp
$./robin_hood_test
[std::unordered_map] Time: 1145 ms. Sum: -1455759936
[robin_hood::unordered_map] Time: 918 ms. Sum: -1455759936