Finding the highest distinct integer in a list of a list

hoping someone can help me out with something. I have an object which contains a list of values and an identifier similar to this:

public class MyObj
{
    public string Id { get; set; }
    public List<MyOtherObj> OtherObject { get; set; }

    public class MyOtherObj
    {
        public int Score { get; set; }
    }
}

I then have a method similar like this:

    public MyObj GetHighestScoreThatIsNotDuplicated(IEnumerable<MyObj> myObjs)
    {
        //Not sure what to do here

        return new MyObj();
    }

So now if you imagine the input being along these lines:

MyObj1: Id = 1, OtherObj (list of score) = 5,4,3,2,1

MyObj2: Id = 2, OtherObj (list of score) = 10,5,4,3,2

From here the MyObj2 should be returned as 10 is the highest score and it is not present within the other list.

However if the input was:

MyObj1: Id = 1, OtherObj (list of score) = 5,4,3,1

MyObj2: Id = 2, OtherObj (list of score) = 5,4,3,2,1

MyObj3: Id = 3, OtherObj (list of score) = 5,4,3,1

Then the output would be MyObj2 as 5, 4 & 3 are in all the lists however 2

I’m imagining this will be some kind of recursive method which is fine but I just can’t think how to do this in any kind of a clean way.

>Solution :

How efficient does it have to be? A trivial solution might involve the following steps:

1. Count each score value
2. Only select scores with count==1
3. Select highest score
4. Find object which contains this score

Something like:

var groupedScores = myObjs
    .SelectMany(o => o.OtherObject)
    .Select(o => o.Score)
    .GroupBy(x => x);
var highestScore = groupedScores
    .Where(g => g.Count() == 1)
    .SelectMany(x => x)
    .Max();
var result = myObjs
    .FirstOrDefault(o => o.OtherObject.Any(x => x.Score == highestScore));