Add Bubble Sort in Pascal (TheRenegadeCoder#4801)

Author: pascalecu

archive/p/pascal/bubble_sort.pas

@@ -0,0 +1,116 @@
+program BubbleSort;
+
+{$mode objfpc}{$H+}
+
+uses
+   Classes, Generics.Collections, SysUtils;
+
+type
+   TIntegerList = specialize TList<Integer>;
+
+procedure ShowUsage;
+begin
+   Writeln('Usage: please provide a list of at least two integers to sort in the format "1, 2, 3, 4, 5"');
+   Halt(1);
+end;
+
+function ParseIntegerList(const S: string): TIntegerList;
+var
+   Tokens: TStringArray;
+   Token: string;
+   Value: Integer;
+begin
+   if S.Trim.IsEmpty then
+      ShowUsage;
+
+   Tokens := S.Split([',']);
+   Result := TIntegerList.Create;
+
+   for Token in Tokens do
+   begin
+      if not TryStrToInt(Trim(Token), Value) then
+      begin
+         Result.Free;
+         ShowUsage;
+      end;
+      Result.Add(Value);
+   end;
+
+   if Result.Count < 2 then
+   begin
+      Result.Free;
+      ShowUsage;
+   end;
+end;
+
+function IsSorted(const A: TIntegerList): Boolean;
+var
+   i: Integer;
+begin
+   for i := 1 to A.Count - 1 do
+      if A[i] < A[i - 1] then
+         Exit(False);
+   Result := True;
+end;
+
+procedure BubbleSort(List: TIntegerList);
+var
+   i, j: Integer;
+   Swapped: Boolean;
+
+   procedure SwapElements(Index1, Index2: Integer);
+   var
+      Temp: Integer;
+   begin
+      Temp := List[Index1];
+      List[Index1] := List[Index2];
+      List[Index2] := Temp;
+   end;
+begin
+   for i := List.Count - 1 downto 1 do
+   begin
+      Swapped := False;
+      for j := 0 to i - 1 do
+         if List[j] > List[j + 1] then
+         begin
+            SwapElements(j, j + 1);
+            Swapped := True;
+         end;
+
+      if not Swapped then
+         Break;
+   end;
+end;
+
+function FormatIntegerList(List: TIntegerList): string;
+var
+   i: Integer;
+begin
+   Result := '';
+   for i := 0 to List.Count - 1 do
+   begin
+      if i > 0 then
+         Result += ', ';
+      Result += IntToStr(List[i]);
+   end;
+end;
+
+var
+   RawInput: string;
+   Numbers: TIntegerList;
+begin
+   if ParamCount <> 1 then
+      ShowUsage;
+
+   RawInput := ParamStr(1);
+   Numbers := ParseIntegerList(RawInput);
+   try
+      if not IsSorted(Numbers) then
+         BubbleSort(Numbers);
+
+      Writeln(FormatIntegerList(Numbers));
+   finally
+      Numbers.Free;
+   end;
+end.
+