tyvj P1001 第K极值

program p1001;
 var
  i,tot,j,s,m,n,k:longint;
  a:array[1..10000]of longint;
 function prime(x:longint):boolean;
  var
   t,temp:longint;
  begin
   if (x=1) or (x=2)then exit(true);
   temp:=trunc(sqrt(abs(x)))+1;
   prime:=true;
   for t := 2 to temp do if (x mod t = 0) then exit(false);
  end;
 begin
  read (n,k);
  for i := 1 to n do read (a[i]);
  for i := 1 to n do
   for j := 1 to n do
    if a[i]>a[j] then
     begin
      tot:=a[i];a[i]:=a[j];a[j]:=tot;
     end;
  s:=a[k]-a[n+1-k];
  if (not(prime(s)) or (s<2))then writeln('NO')else writeln('YES');
  writeln(s);
 end.

 

 http://www.tyvj.cn:8080/Problem_Show.asp?id=1001

还算顺利，发现最弱智的排序都能不超时，暂时就不写快排了吧~

P1002

谁拿了最多奖学金，读入搞不定。。郁闷，明天重试~