sort within category and limit 5 for this hive table

Question

I have a hive table A that has the following column

USER   ITEM    SCORE
U1      I1       S1
U1      I2       S2
...................

What I wan

Answer 1

should be something like this :

select USER,collect_set(ITEM) from (
    select USER, ITEM,row_number () over (partition by USER order by SCORE desc) RN 
    from A
) t1
where RN <= 5
group by USER;