Todo

# TODO

## Strategies

[x] Two string kite
[ ] Simple coloring
[x] W wing
[ ] Finned swordfish
[ ] Fireworks
[ ] Empty rectangle
[ ] Empty rectangle but as a Grouped Nice Loop
[ ] Coloring with >1 candidate (3d Medusa)
[ ] More wings?
[ ] Sue-de-coq
[ ] Exocet
[ ] Wow

### Speed

Premature optimization is bad, but this is the most exciting part of the code.

[ ] Generalize strategies with a better API
[ ] Switch ordering of loops: I think having the candidate loop be in the inner loop is much faster
[ ] Hidden pairs, triples, and quads is much faster than pairs, triples, and quads
[ ] Make XY Loop and XY Chain be able to short circuit (i.e. not include the starting cell).
    This would allow us to skip cells that are already connected, bounding the strategies to n^4
    The strategies are already really fast, so do some testing first.

## Code

[ ] Migrate undo functionality completely to the solver
[ ] Make rtl handling consistent in the css files
[ ] rtl keyboard navigation should be inverted?

## Features

[ ] Better cell highlighting/selection (And set aria-selected and aria-multiselectable)
[ ] Better cell navigation
[ ] Better sudoku api

[ ] More sudoku editing controls
> depends on:
>
> Better cell highlighting
> Better sudoku api

[ ] Sudoku titles
[ ] Sudoku info, like the author and date

## Unimportant

[ ] Fix tabs.test.tsx
[ ] Fix sonar-js/cognitive-complexity errors
   [ ] checkValidity
   [ ] fish
   [ ] hiddenPairsTriplesAndQuads
   [ ] hiddenSingles
   [ ] intersectionRemoval
   [ ] pairsTriplesAndQuads
   [ ] skyscraper x2
   [ ] twoMinusOneLines x2
   [ ] updateCandidates
   [ ] xyChain
   [ ] xyLoop
   [ ] xyzWing
   [ ] yWing
[ ] Better comments
   [ ] Better explanation for hiddenPairs... and pairs...