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

I usually frown on solutions that involve captured variables, but I had an urge to write this:

bool hasRepeating = false;
int previous = 0;

int firstDuplicateValue = a
  .Where(i => i != 0)
  .OrderBy(i => i)
  .FirstOrDefault(i => 
  {
    hasRepeating = (i == previous);
    previous = i;
    return hasRepeating;
  });

if (hasRepeating)
{
  Console.WriteLine(firstDuplicateValue);
}