Factorial generator

Simple factorial generator written in JavaScript. This utility function uses bigNumber

Factorial Definition

The Factorial of a number n, can be defined by:

  n! = (n-1)! * n
  0! = 1

Algorithm and reasoning

• bigNumber : An external library is used as JavaScript safe integer limits to (2^53) - 1
• Used iterative approach instead of recursive due to performance
• Memoization is used to store the results. Thus, cached results are used for future computations

Room for improvement

• Memoization is costing space.
  • It took 40MB(approx.) for an array to store factorials of first 2000 integers
  • We can watch the trend for n and optimize the cache array
    • We can warm up this cache array during initialization
    • We can put an upper limit for this this cache array

Credits

• Big number handling