X-Sudoku has extra rule for diagonals which give extra hints for diagonal cells. Does this implies that solving X-Sudoku puzzles are easier than classic Sudoku puzzles?

  • $\begingroup$ What is "easier" is subjective and varies between person to person based on a variety of factors $\endgroup$
    – bobble
    Jan 7, 2022 at 18:47
  • $\begingroup$ Take it as an algorithmic/ mathematical approach by computer $\endgroup$ Jan 7, 2022 at 18:49
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    $\begingroup$ What algorithms? What mathematics? How are we defining "easier" objectively? And what exactly are we comparing? All possible Sudokus vs all possible X-Sudokus? Puzzles that are considered of similar difficulty within one puzzle type? $\endgroup$
    – bobble
    Jan 7, 2022 at 18:49
  • $\begingroup$ @bobble I would argue here that while easier is subjective, sudokus can be ranked in difficulty so you can actually assign a difficulty level to every sudoku and compare. In a mathematical sense, sudoku difficulty can be compared, although this should be made clear in the question too $\endgroup$ Jan 7, 2022 at 18:52
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    $\begingroup$ @BeastlyGerbil that's basically my point: this needs some more detail, more explanation of what it means, to improve it, I think $\endgroup$
    – bobble
    Jan 7, 2022 at 18:57

1 Answer 1


Not necessarily.

The difficulty level of sudoku is not determined by the amount of restrictions there are on the puzzle, but rather the level of skill and techniques required to solve the puzzle. The easiest of sudoku puzzles will require basic understanding of sudoku logic, whereas the hardest will require advanced techniques and understanding.

There is another question here on the site which discusses how difficulty is determined, and sudokuoftheday show their ranking system, where they'll assign a 'score' to each technique used and by adding up these scores assign a value to the puzzle.

These can range from a score of 100 for a single candidate, to 2800 for an X-Wing, to 8000 for a Swordfish which is considered the hardest technique. A single swordfish technique used would by their ranking make the puzzle the second highest difficulty level.

While a X-Sudoku may have extra restrictions which may give more information, it won't necessarily make it easier. Designed well, the creator could incorporate the extra information given by the restriction into the puzzle such that you have to use the information to solve. If done right, it may make it even harder than a normal sudoku by incorporating higher level techniques only applicable to X-Sudokus.

So overall, an X-Sudoku might be easier than a normal Sudoku, but it won't simply be because of the puzzle type. The design of the puzzle and techniques required are the main factor here.

  • $\begingroup$ Thanks for this detailed explanation, I will study more how difficulty rating of the classic sudoku is determined. $\endgroup$ Jan 7, 2022 at 18:54

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