Cod sursa(job #575373)

Utilizator andreifirstCioara Andrei Ioan andreifirst Data 8 aprilie 2011 11:15:08
Problema Statistici de ordine Scor 70
Compilator fpc Status done
Runda Arhiva educationala Marime 0.83 kb
var v:array [1..3000000] of longint;
    buf1:array[1.. 1 shl 17] of char;
    i, n, k, aux, q:longint;
    f, g:text;

procedure qsort (st, dr:longint);
var s, d, p:longint;
  begin
  p:=random(dr-st+1)+st;
  aux:=v[p]; v[p]:=v[st]; v[st]:=aux;
  s:=st; d:=dr;
  while s < d do
    begin
    while (v[d]>=aux) and (s<d) do d:= d-1;
    v[s]:=v[d];
    while (v[s]<=aux) and (s<d) do s:= s+1;
    v[d]:=v[s];
    end;
  v[s]:=aux;
  if k <= s then
    begin
    if k = s then exit
             else qsort (st, s-1);
    end
            else begin qsort (s+1, dr); end;
  end;

begin
assign (f, 'sdo.in'); settextbuf (f, buf1); reset (f);
assign (g, 'sdo.out'); rewrite (g);
randomize;

read (f, n, k);
for i := 1 to n do read (f, v[i]);

qsort (1, n);
q:=v[k];
writeln (g, q);

close (f); close (g);
end.