set nocount on;
declare @t table(ID int, Count int);

insert @t values(1, 18)
insert @t values(2, 6)
insert @t values(3, 11)
insert @t values(4, 1)
insert @t values(5, 6)

declare @cnt int;
set @cnt=37;

with
ordered as (select *, ROW_NUMBER() over(order by Count DESC) as n from @t)
,
x as (
select top(1) CAST(0 as int) as total
     , CAST(null as int) as count
     , CAST(null as int) as id
     , CAST(null as int) as count0
     , cast( 0 as bigint ) as n 
union all
select case when x.total+o.count >=@cnt then @cnt else x.total+o.count end as total
      , case when x.total+o.count <= @cnt then o.count else (@cnt - x.total) end
      , o.id
      , o.count
      , o.n 
from x inner join ordered o on x.n+1 = o.n
  where x.total<@cnt
 )
select * from x; 

insert @t values(1, 1)
insert @t values(2, 2)
insert @t values(3, 3)
insert @t values(4, 7)
insert @t values(5, 13)
insert @t values(6, 21)
insert @t values(7, 34)
insert @t values(8, 55)
insert @t values(9, 89)
insert @t values(10, 144)
insert @t values(11, 200)