Question

Well, I’m having trouble with this code, it’s about writing the Selection Sort alghorithm in Mathematica, but inverted, I mean, instead of searching for the smallest number and place it in the first position of a list, I need to search for the biggest one and place it in the last position.
I’ve written this code but as I’m new to Mathematica, I can’t find the solution. It doesn’t sort the list. Thank you very much for reading, your answers will be helpfull!

      L = {};
n = Input["Input the size of the list (a number): "];
For[i = 1, i <= n, m = Input["Input a number to place in the list:"]; 
 L = Append[L, m]; i++]
SelectSort[L] := 
 Module[{n = 1, temp, xi = L, j}, While[n <= Length@L, temp = xi[[n]];
   For[j = n, j <= Length@L, j++, If[xi[[j]] < temp, temp = xi[[j]]];];
   xi[[n ;;]] = {temp}~Join~
     Delete[xi[[n ;;]], First@Position[xi[[n ;;]], temp]];
   n++;];
  xi]
Print[L]

Answer 1

Here is a working version. In the SelectSort[] function I only had to change the function variable to a pattern variable, i.e. L_. Other than that it seems to work.

(* Function definition *)
SelectSort[L_] := Module[{n = 1, temp, xi = L, j},
  While[n <= Length@L,
   temp = xi[[n]];
   For[j = n, j <= Length@L, j++,
    If[xi[[j]] < temp, temp = xi[[j]]];
    ];
   xi[[n ;;]] = {temp}~Join~
     Delete[xi[[n ;;]], First@Position[xi[[n ;;]], temp]];
   n++;];
  xi]

(* Run section *)
L = {};
n = Input["Input the size of the list (a number): "];
For[i = 1, i <= n, m = Input["Input a number to place in the list:"];
 L = Append[L, m]; i++]
SelectSort[L]
Print[L]

{3, 3, 5, 7, 8}

{8, 3, 5, 7, 3}

The output is first the sorted list from SelectSort[L], then the original input list,L.