Implement an Atomic Counter (Thread-Safe Counter)

Implement a thread-safe counter AtomicCounter. APIs increment() -> int: atomically increments by 1 and returns the new value. get() -> int: returns the current value. Requirements Using synchronized (or equivalent mutex) is allowed. Discuss performance bottlenecks under high contention and possible optimizations (CAS/LongAdder) verbally. Scale 100+ threads, up to 1e6 total operations. Example Input 2 threads each increment 100000 times Output final get() == 200000