null was redundant

Your hash map have race condition.

T1: get value from hash map for username "Steve"
T2: get value from hash map for username "Steve" too
T1: set counter value for "Steve" to 1
T2: set counter value for "Steve" to 1

But this should be 2 and addings atomic long here not solve this problem. You should sync access to hash map or use concurrent hash map with atomic operations like 'compute'

A bit naive solution, try doing it without recursion. Extra space is not good at all.

Can you elaborate on these parts?
round = round > SVEN.length - 1 ? 0 : round;
return HUGH[round++];

Can you elaborate bit more on getStatisticsWinner() ?

Limited number of cases, just storing and returning the solution for each n.

Please do explain !?