Sudoku algorithm in C#

Question

I need one liner (or close to it) that verifies that given array of 9 elements doesn\'t contain repeating numbers 1,2,3,...,9. Repeating zeroes do not count (they represent empt

Answer 1

Why do you want a convoluted line of Linq code, rather than wrapping up an efficient implementation of the test in an extension method and calling that?

var a = new int[9] {1,2,3,4,5,6,7,8,9};
var itIsOk = a.HasNoNonZeroRepeats();

One implementation of NoNonZeroRepeats could be to use the 9 lowest bits of a short to indicate presence of a value in the array, giving an O(length(a)) test with no dynamic memory use. Linq is cute, but unless you're only using it for aesthetic reasons (you don't specifically say that you're writing a sudoku solver using only Linq as an exercise) it seems to be just adding complexity here.