SQL> ed
Wrote file afiedt.buf

  1  with t (
  2  num1,       num2,   num3,   num4) as (
  3  select  123,        222,    333,    10 from dual union all
  4  select  null,       null,   444,    1 from dual union all
  5  select  123,        222,    333,    10 from dual union all
  6  select  null,       null,   444,    1 from dual)
  7  select
  8    LAST_VALUE(num1 ignore nulls) OVER (order by num1,num2,num3) n1
  9   ,LAST_VALUE(num2 ignore nulls) OVER (order by num1,num2,num3) n2
 10   ,num3
 11   ,sum(num4) n4
 12* from t group by num1,num2,num3
SQL> /

        N1         N2       NUM3         N4
---------- ---------- ---------- ----------
       123        222        333         20
       123        222        444          2

SQL>