在 c# 中合并 2 个自定义 List 对象

Question

Can someone help me out or can give me any pointer of solving this particular issue. Merging of list objects, by comparing 2 List of objects.

It is manageable with simple for loops and linq, as data is huge I was searching for optimum way or any algorithm for this purpose would be of great help.

class user
{
    string userID;
    string userName;
    //...
    List<role> objRoles;
}
class role
{
    List<pemission> objPermisison;
}
class pemission
{ 
    bool newlyAdded;
    //...
}

List<User> List1 :

User1      
 - Role_1
     - Permission_1 
     - Permission_2 
 - Role_2
     - Permission_3
     - Permission_4 


List<User> List2 :

User1      
 - Role_1
     - Permission_3  
     - Permission_4 
 - Role_2
     - Permission_5
     - Permission_4 


Required Result : 

List<User> Resultant_List :

User1      
 - Role_1
     - Permission_1 
     - Permission_2 
     - Permission_3 - Flag (Newly Added)
     - Permission_4 - Flag (Newly Added)
 - Role_2
     - Permission_3
     - Permission_4 
     - Permission_5  - Flag (Newly Added)

Answer 1

According to here to merge two lists without duplicates, a dictionary merge is the fastest method...

"This solution converts list2 to a dictionary and then it loops a single time over list1. It either adds to the dictionary or replaces the value of list2 if it was a duplicate. This seemed to be a much more efficient algorithm."

var dict = list2.ToDictionary(p => p.userID);

foreach (var person in list1)
{
    dict[person.userID] = person;
}

var merged = dict.Values.ToList();