Calculates whether a number is a happy number as quickly as possible using several techniques including:

• Caching
  • Including recognising permutations of the same digits
• Multi-threading (CPU, not GPU)
  • Including a function to help choose an optimal number of threads to use
• Branch prediction

Default functionality is to time how many milliseconds it takes to cache the happiness of 2,000,000,000 numbers in base 10, outputting every 10,000,000th number, skipping permutations but using a single thread

Made alongside AzureAqua for competitive programming