@jacroberts, ok, maybe the brute force was an exaggeration as rules say ther is only one valid solution @dishdy, that's not all I meant by complexity. Number of initial clues is one factor but depending on the clues you may need to employ different te

I think that is a very important question and probably this challenge need some more details in description. Especially when we are to compete on performance. Simple solution will be fast and deal with majority of simple cases. But a very sophisticated one

Hello, How complex the test puzzles will be? Or in other words how complex solving techniques are we expected to implement? For reference please have a look here http://www.sadmansoftware.com/sudoku/solvingtechniques.htm

@puzzles Thanks

@puzzles Ok, I admit the result was wrong. Silly mistake where I return level instead of the id. I have fixed that but still I have the same problem with the sandbox @Jacob I would very much appreciate such link. I wonder if the problem is with di

@puzzles, Thanks a lot.