Язык не указан → приведу пример на SWI-Prolog.

Код

• %Файл string_sortin.pl
• sort([], [], _).
• sort([Head|Tail], Ordered, Qrd) :-  sort(Tail, SubSorted, Qrd),
•         put(Head, SubSorted, Sorted),
•         order(Sorted, [], Ordered, Qrd).
• put(X, [], [X]).
• put(X, [H|T], [X,H|T]) :- compare(>, X, H).
• put(X, [H|T], [H|R]) :- put(X, T, R).
• order(X, _, X, ">").
• order([], R, R, "<").
• order([H|T], B, R, "<") :- order(T, [H|B], R, "<").
• select(">", Bufer, Bufer, _, ">").
• select("<", Bufer, Bufer, _, "<").
• select(S, Bufer, [S|Bufer], Ord, Ord).
• input_strings(Input, Bufer, Strings, Ord, ROrd) :-
• compare(=, Ord, "="),
• read_string(Input, "\n", "\r", _, String),
• select(String, Bufer, SS, Ord, OO),
• input_strings(Input, SS, Strings, OO, ROrd).
• input_strings(_, Strings, Strings, Ord, Ord).
• ?- current_input(Input), input_strings(Input, [], Strings, "=", Ord), sort(Strings, [R|_], Ord), writeln(R).