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

!a.GroupBy(i => i).Any(gp => gp.Key != 0 && gp.Count() > 1)