Flesh out readme

README.md

@@ -1,6 +1,53 @@
 # Sudoku Solver
 
 Figured it would be fun to try making a sudoku solver. I haven't read
-any prior art but once I have something working I might look into
-faster mechanisms people have come up with (probably using SAT
-solvers).
+any prior art as of yet, though I might at some point to improve
+this. I found [this
+dataset](https://www.kaggle.com/datasets/rohanrao/sudoku) to use for
+testing and benchmarking; it contains 9 million puzzles. I haven't
+included the dataset in this repository as it's quite big (around 1.4
+GiB), but you can download the archive from the above link and place
+the extracted `sudoku.csv` in the root of this repo and it should
+work.
+
+## Building
+
+The program is built with `make(1)`:
+
+```shell
+make # or 'make sudoku'
+```
+
+## Preparation of Puzzles File
+
+I did some pre-processing of the downloaded `sudoku.csv` file to
+reduce the workload of the solver, extracting just the puzzles (the
+CSV contains the solutions too) and removing the newlines.
+
+```shell
+make puzzles
+```
+
+## Preparation of Results File
+
+The results file must exist and be of the right size in order for the
+program to run successfully.
+
+```shell
+make results
+```
+
+## Running
+
+The program can be ran through the Makefile, which will ensure the
+binary is built and the puzzles and results files have been prepared:
+
+```shell
+make run
+```
+
+Or it can of course be ran directly:
+
+```shell
+./sudoku
+```