SayantanScience

Search.solution was unnecessarily synchronising its operations. The only part where it needs synchronisation is the init part. So, we add a (unsynchronized) check there. This will cause the first call...

Some aesthetic changes to make it more user friendly

2

That should be IllegalArgumentException as the argument is illegal, not the internal state. The value key len should be public, or how would one know what is the key length...