For the easy and medium, it seems like you can work outwards from the top left corner, solving progressively larger squares. 1×1, 2×2, etc. Once one of those sq

For the easy and medium, it seems like you can work outwards from the top left corner, solving progressively larger squares. 1×1, 2×2, etc. Once one of those squares is correct, you never have to touch the rows or columns in that square again. Probably not a perfectly efficient strategy but it makes it easier to think about.