thuật toán sắp xếp chuỗi trong pascal

Mời các bạn xem thuật toán này:
program sx;
uses crt;
var
s : array [1..30] of string;
n : integer;
procedure nhap;
var
i : integer;
begin
write(' nhap N : ');
readln(n);
for i:=1 to n do
begin
readln(s[i]);
end;
end;

function sosanh(a,b : string) : integer;
var
kq : integer;
i,j : integer;
begin
for i:=1 to length(a) do
a[i] := upcase(a[i]);
for i:=1 to length(b) do b[i] := upcase(b[i]);
i := 1;
j := 1;
while ( (i<=length(a)) and (j <=length(b)) ) do
begin
if a[i] <> b[j] then
break;
inc(i);
inc(j);
end;
if (i<=length(a)) and (j<=length(b)) then
if a[i] > b[j] then
kq := 1
else
kq := -1
else
if length(a) > length(b) then
kq := 1
else
kq := -1;
sosanh := kq;
end;

procedure sapxep;
var
tam : string;
i,j : integer;
begin
for i:=1 to n-1 do
for j:=i+1 to n do
if sosanh(s[i],s[j]) >= 1 then
begin
tam := s[i];
s[i] := s[j];
s[j] := tam;
end;
for i:=1 to n do
writeln(s[i]);
readln;
end;

begin
nhap;
sapxep;
end.