Complement Lookup Tables

Precompute table[x] for small x (e.g. byte) to answer complements or popcount fast inside inner loops.

Try this in Python

pop8 = [bin(i).count("1") for i in range(256)]
print(pop8[13])

Key takeaways

• Split 32-bit integers into bytes and sum tables—classic micro-optimization pattern.
• Only worth it when profiling shows hotspot.
• Know int.bit_count() in modern Python.