Nissy

A Rubik's cube solver and FMC assistant

Nissy is a command-line Rubik's cube solver. It can find optimal solutions for random positions using techniques from Herbert Kociemba's Cube Explorer and Tomas Rokicki's nxopt. With 4 cores at 2.5GHz and using about 3Gb of RAM, Nissy can find an optimal solution in about a minute on average.

Nissy aims at being a complete tool for FMC (Fewest Moves Challenge) practice. It can solve different steps of Thistlethwaite's algorithm (also know as DR/HTR) and cans use NISS (Normal-Inverse Scramble Switch).

You should use Nissy if:

• You want to analyze your DR solutions or check for multiple optimal (or sub-optimal) solutions for EO/DR/HTR or similar steps.
• You just want a Rubik's cube solver and you like command line interfaces.
• You want an alternative to Cube Explorer.

To get started, head to the download page.

You can also look at its source code by cloning the git repository:

git clone https://git.tronto.net/nissy-classic

For a summary of changes and a list of older versions see the bottom of this page. Some versions (for example 1.0) are not available directly, but can be obtained from the git repository.

Installation

You can get the latest version of nissy at the following links:

System requirements

A full installation of nissy requires about 3.1Gb of space, of which 2.3Gb are occupied by the huge pruning table for fast optimal solving, and running it requires the same amount of RAM. One can choose to never use this function and not to install the relative pruning table. There is an alternative (slower) optimal solving function that uses about 500Mb of RAM. When generating the pruning tables automatically (see the section Tables below), at least 5.3Gb or RAM are required.

Windows

Try downloading and executing in a terminal the file nissy.exe, then follow the instructions in the Tables section below for installing the pruning tables. If nissy.exe does not work, you can try following the UNIX instructions in WSL (Windows Subsystem for Linux) or in a similar environment.

UNIX (Linux, MacOS, *BSD...)

Download the source archive (.tar.gz). Extract it with your favorite archive program, for example with

tar -xvzf nissy-VERSION.tar.gz

Open a terminal in the directory just extracted. If you wish, edit the Makefile to match your local configuration (this is usually not necessary, but you may want to change the PREFIX variable to change the installation path) and run

make

followed by

make install

Then follow the instructions below to install the pruning tables.

Tables

Once you have installed nissy, run

nissy gen

to generate all the tables that Nissy will ever need. Running this command requires around 5.3Gb of RAM, and it can take some time (about 90 minutes on my 9 year old but laptop, with 4 CPU threads).

Some unnecessary technical detail: by default this command is going to use at most 64 threads. If you want you can choose to use more threads (if your CPU is very powerful) or fewer threads (if you for example want to run this command in the background while you do other stuff) with the -t option, for example nissy gen -t 1.

Alternatively, you can download all the tables (1.7Gb) and copy them into the correct folder (see manual page, ENVIRONMENT section). On UNIX operating systems this folder is either .nissy/tables in the user's home directory or $XDG_DATA_HOME/nissy/tables if the XDG variable is configured. On Windows it is the same directory as the nissy.exe executable file.

Upgrading

Upgrading from 2.0.4 or later to any later version: Follow the general upgrading instructions below, no other step required.

Important note for upgrading to 2.0.4: A bug in 2.0.3 and earlier versions caused HTR-related tables to be generated incorrectly on ARM platforms (Mac M1, Android...). If you are upgrading to 2.0.4 on such a device, you need to re-generate these tables. You can do this by removing all the files wiht htr in their name and let nissy re-generate them (after upgrading), or by downloading the new tables and replacing the old ones.

General upgrading instrutions If you already have nissy installed and you want to upgrade to a more recent version, you can simply repeat the installation process:

• On Windows: simply replace nissy.exe with the new file with the same name.
• On UNIX systems: download the new version of the source code, extract it in a new folder and run make and make install again.

Between each version new table files might have been added, or old ones may be not used anymore. Nissy will deal with this automatically unless otherwise reported in this page (see above).

Version history

Nissy v2

Nissy v1

Nissy v1 was released in 2020. It was slow, full of bugs and the code was quite terrible. But in practice it got its job done most of the time.