The Sudoku number-filling puzzle is world famous and has been for quite some time. Due to the various degrees of difficulty the puzzle may provide, people of all ages and levels of intelligence compete against it and have chances of winning. We want to present the world’s most difficult Sudoku puzzle, considered unwinnable for people. As we will see later on, there are some places we can get help to solve such complicated puzzles, mainly using computer-generated code.
Difficulty increase in Sudoku not only comes from the scarcity of numbers on the Sudoku board, but also from how they are placed. Less numbers to begin with most often lead to a greater difficulty. Sudoku difficulty is measured on a scale of five stars, five being the highest. The most difficult puzzles often exceed those five stars in a spectacular manner, as we are about to see below.
What is often considered the world’s most difficult Sudoku was created by a Finnish mathematician, Arto Inkala. He has stated that there are a lot of variants in which the puzzle can be formulated and even the sharpest minds cannot figure out its solution. The difficulty calculated based on the 5-star approach went way beyond the initial scale, scoring an impressive 11 stars. This is why this puzzle was not used in the World Sudoku Championships.
A normal game of Sudoku is based on you filling out numbers based on the ones that are already available,
with only one possible solution at the end of each logic cycle you make. For the one designed by Mr. Inkala, there is no singular solution, there are at least 2 possibilities for each logic cycle. After performing one logic cycle, you will choose the option you think is best. After which you will continue with logic cycle after logic cycle, with one two possible alternatives : either you complete the entire board with no errors (highly unlikely) or you reach a point where you clearly see an impossibility, which means that one of the decisions you made along the way was wrong.
This means that the person who wants to solve it (best of luck!) must examine all possibilities, out of which only one will be correct in the end. This is the exact reason why this is considered to be the world’s most difficult Sudoku. With the number of distinct solutions being around a few thousands, one can expect that no human will be able to crack the puzzle. It has been solved by a computer-generated algorithm at some point in the last few years, not without some sweating from its part. Now we no longer have to worry about wasting hours and hours of our lives trying to find solutions to difficult Sudoku puzzles. Thank God, computers can do that for us.
Thus, we can all go back to our newspaper Sudoku puzzles, unless we have a powerful computer and good coding skills. Even then, it could be a lot more fun to call it “unsolvable” and play Sudoku the old-fashioned pen-and-paper way.