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 solve travelling-salesman-problem sort travelling-salesman-problem-solution ascending sort travelling-salesman-problem-solution descending sort travelling-salesman-problem-solution ascending then descending

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
24 apr 2019 3:41 pm edt:input-format for 'solve travelling-salesman-problem' button is [point-1],[point-2],[distance-between-point-1-and-point-1];[point-2],[point-3],[distance-between-point-2-and-point-3]
example-input-1 for 'solve travelling-salesman-problem' button
1,2,1;1,3,2;2,1,3;2,3,4;3,1,5;3,2,6
example-input-2 for 'solve travelling-salesman-problem' button
1,2,1; 1,3,2; 1,4,3; 2,1,3; 2,3,4; 2,4,5; 3,1,5; 3,2,6; 3,4,7; 4,1,1; 4,2,2; 4,3,3
24 apr 2019 4:40 pm edt:example-input for 'produce permutation' button
1,2,3
25 apr 2019 9:57 am edt:example-input-3 for 'solve travelling-salesman-problem' button taken from https://developers.google.com/optimization/routing/tsp from google(travelling salesman problem solution)page 2 number 2
a,b,10; a,c,35; a,d,30; b,a,10; b,c,30; b,d,15; c,a,35; c,b,30; c,d,30; d,a,30; d,b,15; d,c,30
24 may 2019 6:53 pm edt:example-input-4 for 'solve travelling-salesman-problem' button,which show error 1,2,3;1,3,4
;;