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var friendsOfFriendsofJoe = friendsOfJoe
    .SelectMany(name => friendsByPerson.TryGetValue(name, out var myFriends) ? myFriends : Enumerable.Empty<string>())
    .Except(friendsOfJoe)
    .Where(name => name != "Joe");

static class GraphExtensions
{
    public static IReadOnlyDictionary<string, IEnumerable<string>> FriendsByPerson(this IEnumerable<(string n1, string n2)> source)
    {
        return source.GroupBy(p => p.n1).ToDictionary(g => g.Key, g => g.Select(p => p.n2));
    }
    
    public static Func<string, IEnumerable<string>> FriendsOfFriends(this IReadOnlyDictionary<string, IEnumerable<string>> friendsByPerson)
    {
        return name =>
        {
            if (!friendsByPerson.TryGetValue(name, out var friends)) 
            {
                return Enumerable.Empty<string>();
            }
            
            return friends
                .SelectMany(f => friendsByPerson.TryGetValue(f, out var foaf) ? foaf : Enumerable.Empty<string>())
                .Except(friends)
                .Where(f => f != name);
        };
    }
}

...

Func<string, IEnumerable<string>> foafByPerson = people.FriendsByPerson().FriendsOfFriends();
foreach (string foaf in foafByPerson("Anna"))
{
    Console.WriteLine(foaf);
}

public static IReadOnlyDictionary<string, IEnumerable<string>> FriendsByPerson(this IEnumerable<(string n1, string n2)> source)
{
    return source
        .Concat(source.Select(p => (n1: p.n2, n2: p.n1)))
        .GroupBy(p => p.n1)
        .ToDictionary(group => group.Key, group => group.Select(p => p.n2));
}

Quote:

think the game designers should bear some responsibility here as well...

Quote:

Katie Phillips' daughter reset security settings to accept her own fingerprint to make purchases

OriginalGriff wrote:

You don't mean ...

Jörgen Andersson wrote:

Having so bad security that the daughter could change the fingerprint for appstore is remarkable, imao.

Quote:

after her eight-year-old daughter

Mycroft Holmes wrote:

I would suspect the parents did not set up a fingerprint authorisation

Quote:

Ms Phillips, 35, said: "I felt sick and was in floods of tears. ... It was hard to be too angry with her because she didn't really know what she was doing and she didn't understand.