So I have a list of DefaultSearchModal items that have an enum called TypeSearch in every list item. I would like to order the list to have a different enum property each row.
So if you have an unordered list by this:
1,1,2,2,3,3,4,4,5,5,5,5,5,5
I would like to order it to:
1,2,3,4,5,1,2,3,4,5,5,5,5,5
What would be a good algorithm to sort it like this?
public class DefaultSearchModel
{
public int Id { get; set; }
public string Title { get; set; }
public string Description { get; set; }
public string Url { get; set; }
public TypeSearch TypeSearch { get; set; }
}
public enum TypeSearch
{
News = 0,
Blog = 1,
Photo = 3,
Page = 4
}
5
Personally I would just put it in a loop Here’s psudo code for it.
while mainList has items
{
find first 0 item.
add to queue,
remove from mailList
find first 1 item
add to queue,
remove from mailList
find first 3 item.
add to queue,
remove from mailList
find first 4 item.
add to queue,
remove from mailList
}
return queue
2
The end result thanks to bowlturner:
private IEnumerable<DefaultSearchModel> Sort(IList<DefaultSearchModel> items)
{
var returnList = new Collection<DefaultSearchModel>();
while (items.Any())
{
foreach (var type in Enum.GetValues(typeof (TypeSearch)))
{
if (items.Any(x => x.TypeSearch == (TypeSearch) type))
{
var item = items.FirstOrDefault(x => x.TypeSearch == (TypeSearch) type);
returnList.Add(item);
items.Remove(item);
}
}
}
return returnList;
}
1
My FP-flavored solution:
IEnumerable<DefaultSearchModel> DoMagic(IEnumerable<DefaultSearchModel> models)
{
var groups = models.GroupBy(model => model.TypeSearch);
var solution = Enumerable
.Range(0, groups.Max(grp => grp.Count()))
.SelectMany(i => groups
.Where(grp => grp.Count() > i)
.Select(grp => grp.ElementAt(i))
.OrderBy(model => model.TypeSearch));
return solution;
}
Probably not most efficient either (since I pointed out that @Jamie’s solution isn’t, I can’t be a hypocrite), but it is not my point right now. I just wanted to show how terse and non-imperative LINQ can be.
Note that we are not repeatedly looking for TypeSearch values that aren’t on the list at all, or whose count is beyond a specific treshold.
2
- Go once through the list and divide them up in 5 sets.
- Then simply take one object (if available) from each set in order, and put them into
your output list - Repeat step 2 until all sets are empty
Algorithm has O(n)