Search two lists for at least one match with LINQ

Question

What is the best way (on average) to compare two lists with LINQ (query syntax or otherwise)

var A = new [] { 1, 2, 3, ... };
var B = new [] { 4, 1, 5, ... };

bool match = 
    // Some LINQ expression

such that match will be true when at least one element in the first list (1 in this case) equals an element from the second? I don't need to know how many matches there were, or even which one was matched, just that there was at least one match.

Answer 1

Sure there is.

A.Intersect(B).Any();

Intersect is always useful in the least expected circumstances.

Answer 2

You could use Intersect, but that would calculate all matches, which you don't need. So Any is better, since it will short-circuit:

bool match = A.Any(a => B.Any(b => b == a));

Answer 3

you can also use

A.Any(x => B.Contains(x))

Answer 4

You're looking for a combination of Intersect and Any

bool match = A.Intersect(B).Any();