with c(id, pack, amount)
as
(
select 0, 'pack_0', 20 from dual
union all
select 1, 'pack_1', 10 from dual
union all
select 2, 'pack_2', 3 from dual
union all
select 3, 'pack_3', 2 from dual
union all
select 4, 'pack_4', 1 from dual
),
t as
(select c.*,
        sum(amount) over (order by amount) x,
        sum(amount) over () total
   from c)
select t.*,
       width_bucket(x, 0, total + 1e-10, 3) bkt0,
       -- или что то же самое
       ceil(x / (total / 3)) bkt1
  from t
order by 1;

        ID PACK       AMOUNT          X      TOTAL       BKT0       BKT1
---------- ------ ---------- ---------- ---------- ---------- ----------
         0 pack_0         20         36         36          3          3
         1 pack_1         10         16         36          2          2
         2 pack_2          3          6         36          1          1
         3 pack_3          2          3         36          1          1
         4 pack_4          1          1         36          1          1

with c(id, pack, amount)
as
(
-- select 0, 'pack_0', 100 from dual
-- union all
select 1, 'pack_1', 10 from dual
union all
select 2, 'pack_2', 3 from dual
union all
select 3, 'pack_3', 2 from dual
union all
select 4, 'pack_4', 1 from dual
),
t as
(select c.*,
        sum(amount) over (order by amount) x,
        sum(amount) over () total
   from c)
select t.*,
       width_bucket(x, 0, total + 1e-10, 3 - 1) bkt0,
       -- или что то же самое
       ceil(x / (total / (3 - 1))) bkt1
  from t
order by 1;

        ID PACK       AMOUNT          X      TOTAL       BKT0       BKT1
---------- ------ ---------- ---------- ---------- ---------- ----------
         1 pack_1         10         16         16          2          2
         2 pack_2          3          6         16          1          1
         3 pack_3          2          3         16          1          1
         4 pack_4          1          1         16          1          1

with tt(ord, x)
     as (select rownum, column_value from table(sys.odcinumberlist(1, 2, 3, 10, 100))),
     t0 as (select rownum n from dual connect by level <= power(3, 5)),
     t1 as (select n, mod(trunc(n / power(3, ord - 1)), 3) basket, sum(x) amount,
                   listagg(x, ', ') within group (order by x) items
              from t0 cross join tt
             group by n, mod(trunc(n / power(3, ord - 1)), 3)),
     t2 as (select t1.*,
                   variance(amount) over (partition by n) v,
                   count(*) over (partition by n) cnt
              from t1)
select distinct
       listagg(amount, ', ') within group (order by amount) baskets,
       listagg('(' || items || ')', ', ') within group (order by items) items
  from (select t2.*, rank() over (order by v) rnk
          from t2
         where cnt = 3)
 where rnk = 1
 group by n;

BASKETS                        ITEMS
------------------------------ ------------------------------
6, 10, 100                     (1, 2, 3), (10), (100)