确定许多变量是否唯一的最优雅/最有效的方法是什么？

Question

If I have five variables

int a,b,c,d,e;

What is the most efficient way to make sure they are all unique?

if(a!=b && a!=c && a!=d && a!=e && b!=c && b!=d && b!=e && c!=d && c!=e && d!=e)
{ 
   //Is this the most efficient way??
}

Answer 1

Elegant

int[] arr = { a, b, c, d, e };

bool b = arr.Distinct().Count() == arr.Length;

Efficient

Your code is the most efficient

I guess that is the most simple explanation of your question.

Answer 2

That pretty much is the most efficient way. It's not necessarily the best looking code I've seen but it'll work just fine. Any other solution involving data structures or functions is unlikely to be faster.

I'd recode it for beauty though:

if (a != b && a != c && a != d && a != e
           && b != c && b != d && b != e
                     && c != d && c != e
                               && d != e
) { 
    // Blah blah blah
}

Not necessarily exactly like that, just something a bit easier on the eyes when reading.

Answer 3

I would think something like:

int[] x = new int[] {a,b,c,d,e};
if (x == x.Distinct().ToArray())
{
}

Answer 4

If we're playing code golf we can knock this all down to one line and shave 6 characters:

bool d = (new int[]{ a, b, c, d, e })
              .GroupBy(i => i)
              .Where(i => i.Count() > 1)
              .Any();