Lee Hsein Loong's Sudoku Solver in C++

Not to be discouraging, but if you don't get many comments or votes, it might be because this has been submitted multiple times over the past couple of weeks:

https://news.ycombinator.com/item?id=9487060 2 hours ago, no comments

https://news.ycombinator.com/item?id=9486301 3 hours ago, no comments

https://news.ycombinator.com/item?id=9485348 7 hours ago, no comments

https://news.ycombinator.com/item?id=9485266 8 hours ago, no comments

https://news.ycombinator.com/item?id=9485237 8 hours ago, 136 comments

https://news.ycombinator.com/item?id=9419035 12 days ago, 125 comments