ac1028.pas

同济大学 Online在线题库 AC源代码合集 程序设计竞赛必看资料

program tju1028;
var
  b:array['a'..'z']of boolean;
  m,n,i,j:longint;
  s:string[3];
  c:char;
  first:boolean;
begin
  readln(m);
  for i:=1 to m do begin
    readln(n);
    fillchar(b,sizeof(b),0);
    b['a']:=true;
    for j:=1 to n do begin
      readln(s);
      b[s[1]]:=b[s[3]];
    end;
    first:=true;
    for c:='a' to 'z' do
      if b[c] then begin
        if first then first:=false else write(' ');
        write(c);
      end;
    if first then writeln('none') else writeln;
  end;
end.