permutation-code from https://www.nayuki.io/page/next-lexicographical-permutation-algorithm#18_apr_2019_5_34_pm_edt maybe from google(permutation algorithm),to copy text:find 'problem: copy text' under date '11 nov 2018 10:28 am est' in howto.htm) 1,2,3

produce permutation

console :

18 apr 2019 6:31 pm edt:creation
21 apr 2019 2:1 pm edt=>2:8 pm edt:goal: 'The most direct solution would be to try all permutations (ordered combinations) and see which one is cheapest (using brute-force search). The running time for this approach lies within a polynomial factor of O(n!), the factorial of the number of cities, so this solution becomes impractical even for only 20 cities.' in https://en.wikipedia.org/wiki/Travelling_salesman_problem#22_jul_2018_2_55_pm_edt ;;