permutation generation to use memoized code

[arcturusannamalai]

Permutation generation code as-is is very inefficient; It should be using pre-calculated permutations from 1-8 or so and cache data as it goes along to be efficient for longer calculations.

Current implementation is a total O(n!) implementation; significant gains can be achieved by making it O( (n-8)! ) + memoized.