在带索引的字典中选择List<string>

Dictionary<int, List<string>> userInterests = new Dictionary<int, List<string>>();

// 添加用户及其兴趣爱好
userInterests[1] = new List<string> { "Reading", "Traveling" };
userInterests[2] = new List<string> { "Sports", "Music" };

// 查找用户的兴趣爱好
if (userInterests.TryGetValue(1, out var interests))
{
    Console.WriteLine("User 1 interests: " + string.Join(", ", interests));
}

if (userInterests.TryGetValue(3, out var interests))
{
    Console.WriteLine("User 3 interests: " + string.Join(", ", interests));
}
else
{
    Console.WriteLine("User 3 not found.");
}

if (userInterests.TryGetValue(1, out var interests) && interests.Count > 0)
{
    Console.WriteLine("User 1 first interest: " + interests[0]);
}
else
{
    Console.WriteLine("User 1 has no interests.");
}