# Sudoku Glitch Found?

We noticed while experimenting with the Sudoku example that when we changed the input numbers into an unsolvable puzzle, the QPU returned an answer that changed inputs. We understand why it’s unsolvable of course but we’re curious why the returned input is changed?

Here was the input:

1 7 6 5 4 3 2 1 9
2 0 0 0 0 0 0 0 7
3 0 0 0 0 0 0 0 6
4 0 0 0 0 0 0 0 5
5 0 0 0 0 0 0 0 4
6 0 0 0 0 0 0 0 3
7 0 0 0 0 0 0 0 2
8 0 0 0 0 0 0 0 1
9 1 2 3 5 4 6 7 8

Output:

1 7 6 5 4 3 2 8 9
2 5 9 1 6 8 4 3 7
3 8 4 7 9 2 1 5 6
4 2 1 9 3 7 8 6 5
5 3 7 8 1 6 9 2 4
6 9 8 4 2 5 7 1 3
7 4 5 6 8 1 3 9 2
8 6 3 2 7 9 5 4 1
9 1 2 3 5 4 6 7 8
The solution is correct

Another run:

1 7 6 5 4 3 2 8 9
2 4 9 8 6 1 5 3 7
3 8 5 2 9 7 1 4 6
4 2 8 1 3 9 7 6 5
5 3 1 7 8 6 9 2 4
6 9 7 4 2 5 8 1 3
7 6 4 9 1 8 3 5 2
8 5 3 6 7 2 4 9 1
9 1 2 3 5 4 6 7 8
The solution is correct

On this next run we also observed the changed input, but no correct solution was found:

1 7 6 5 4 3 2 8 9
2 9 4 8 1 6 5 3 7
3 5 8 2 7 9 4 0 6
4 3 1 6 2 8 7 9 5
5 2 9 1 3 7 8 6 4
6 8 7 4 9 5 1 2 3
7 6 5 9 8 1 3 4 2
8 4 3 7 6 2 9 5 1
9 1 2 3 5 4 6 7 8
Error in row: [3, 5, 8, 2, 7, 9, 4, 0, 6]
The solution is incorrect

And finally, on this run, our input was not changed:

1 7 6 5 4 3 2 1 9
2 9 5 6 1 8 4 3 7
3 4 8 7 9 2 5 8 6
4 3 7 2 8 9 1 6 5
5 8 9 1 3 6 7 2 4
6 2 1 4 7 5 8 9 3
7 5 3 8 6 1 9 4 2
8 6 4 9 2 7 3 5 1
9 1 2 3 5 4 6 7 8
Error in row: [1, 7, 6, 5, 4, 3, 2, 1, 9]
The solution is incorrect

### Comments

1 comment
• Hello,

In the input at the top, the first line is:
1 7 6 5 4 3 2 1 9

But the next three examples have:
1 7 6 5 4 3 2 8 9

And then the last example has the first one again:
1 7 6 5 4 3 2 1 9

So one thing that seems a bit strange is that the first input example has an invalid row:
1 7 6 5 4 3 2 1 9

There can't be repeated numbers in the rows, correct?

Could this be the issue?

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