从列表中获取最小值

Question

I have a class ABC like this

public class ABC{
public int Id {get;set;}
public int UserCount {get;set;}
}

Now I add following records to a list of type ABC

List<ABC> lstABC = new List<ABC>();
lstABC.Add(new ABC(){Id=1,UserCount=5});
lstABC.Add(new ABC(){Id=2,UserCount=15});
lstABC.Add(new ABC(){Id=3,UserCount=3});
lstABC.Add(new ABC(){Id=4,UserCount=20});

I've another list of type int

List<int> lstIds = new List<int>();
lstIds.Add(1);
lstIds.Add(3);
lstIds.Add(4);

Now i want to find out the minimum value of UserCount by comparing both the list where Id in lstABC should match the items presesnt in lstIds . I can get the minimum value of UserCount by using loops but is there any another way to get the value in an optimized way by avoiding loops?

Answer 1

You can use Enumerable.Join to link both lists:

var joined = from id in lstIds
             join x in lstABC 
             on id equals x.Id 
             select x;
int minValue = joined.Min(x => x.UserCount);

This is more efficient than loops since Join uses a set to find matching items.

There's more than one way to skin a cat, this is a little bit less efficient:

int minValue = lstABC.Where(x => lstIds.Contains(x.ID)).Min(x => x.UserCount);

Answer 2

Try below code:

        int min = lstABC.Min(entry => entry.UserCount);
        var a = lstABC.Where(e => e.UserCount == min).FirstOrDefault();
        var resul = lstIds.Where(e => e.Equals(a.Id)).FirstOrDefault();
        var result = lstABC.Where(n =>n.Id == resul).FirstOrDefault();