什么是最有效的方式/算法来比较两个列表，找到这两个表之间的增量？ [英] What is the most efficient pattern/algorithm to compare two lists and find the delta between those two lists?

问题描述

我们有两个列表，假设学生和他们的分数。我想比较这两个列表，找到新的列表和老列表之间的三角洲，然后找到侵入性最小的方式插入或更新到新的列表中的任何变化。什么是解决这个最好的算法？ 。要着眼于改变新的列表和性能的最小金额

We have two lists, let's say students and their scores. I want to compare these two lists and find the delta between the new list and the old list, then find the least intrusive way to Insert or Update into the new list any changes. What is the best algorithm to approach this? Want to focus on minimal amount of changes to new list and performance.

示例代码：

List<ListItem> existingList = new List<ListItem>();
List<ListItem> newList = new List<ListItem>();

public TopLists()
{
  InitTwoLists();
}

private void InitTwoLists()
{
  existingList.Add(new ListItem { Name = "Shane", Score = 100 });
  existingList.Add(new ListItem { Name = "Mark", Score = 95 });
  existingList.Add(new ListItem { Name = "Shane", Score = 94 });
  existingList.Add(new ListItem { Name = "Steve", Score = 90 });
  existingList.Add(new ListItem { Name = "Brian", Score = 85 });
  existingList.Add(new ListItem { Name = "Craig", Score = 85 });
  existingList.Add(new ListItem { Name = "John", Score = 82 });
  existingList.Add(new ListItem { Name = "Steve", Score = 81 });
  existingList.Add(new ListItem { Name = "Philip", Score = 79 });
  existingList.Add(new ListItem { Name = "Peter", Score = 70 });

  newList.Add(new ListItem { Name = "Shane", Score = 100 });
  newList.Add(new ListItem { Name = "Steve", Score = 96 });  // This is change
  newList.Add(new ListItem { Name = "Mark", Score = 95 });
  newList.Add(new ListItem { Name = "Shane", Score = 94 });
  newList.Add(new ListItem { Name = "Brian", Score = 85 });
  newList.Add(new ListItem { Name = "Craig", Score = 85 });
  newList.Add(new ListItem { Name = "John", Score = 82 });
  newList.Add(new ListItem { Name = "Steve", Score = 81 });
  newList.Add(new ListItem { Name = "Philip", Score = 79 });
  newList.Add(new ListItem { Name = "Peter", Score = 70 });
}
}

public void CompareLists()
{
  // How would I find the deltas and update the new list with any changes from old?
}
}

public class ListItem
{
  public string Name { get; set; }
  public int Score { get; set; }
}

**编辑：期望输出的 * 的

所需的输出是实际的增量改变newList。
例如，在这样的场景：

The desired output is to actually change the newList with the deltas. For example in this scenario:

newList.Add(new ListItem { Name = "Shane", Score = 100 });
  newList.Add(new ListItem { Name = "Steve", Score = 96 });  // This is change
  newList.Add(new ListItem { Name = "Mark", Score = 95 });
  newList.Add(new ListItem { Name = "Shane", Score = 94 });
  newList.Add(new ListItem { Name = "Brian", Score = 85 });
  newList.Add(new ListItem { Name = "Craig", Score = 85 });
  newList.Add(new ListItem { Name = "John", Score = 82 });
  newList.Add(new ListItem { Name = "Steve", Score = 81 });
  newList.Add(new ListItem { Name = "Roger", Score = 80 });  // Roger is a new entry
  newList.Add(new ListItem { Name = "Phillip", Score = 79 });  // Philip moved down one

//彼得脱落这份名单与他的70分，因为我只希望前10

// Peter drops off this list with his score of 70, since I only want the top 10.

所以变化将是：

更新记录2史蒂夫比分已经变为
在9位
跌落记录彼得关十大插入新记录罗杰。

Update record 2 for "Steve", the score has changed Insert new record "Roger" at position 9 Drop record for "Peter" off of the top 10.

推荐答案

您可以使用LINQ：

List<ListItem> list1 = GetYourList1();
List<ListItem> list2 = GetYourList2();
var diff = list1.Except(list2);

您例如特定的：

var diff = newList.Except(existingList);

不知道这是最有效的，但是它的简洁：）

Not sure if it is the most efficient but it's concise :)

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