KPLANK – spoj

uses math;
const
  fi='';
  fo='';
  maxn=trunc(1e6)+3;
var
  st : array[1..maxn] of longint;
  a,l,r : array[1..maxn] of longint;
  i,j,n : longint;
  res : int64;
  top : longint;
procedure enter;
  begin
    assign(input,fi);reset(input);
    readln(n);
    for i:=1 to n do read(a[i]);
  end;
procedure push(x : longint);
  begin
    inc(top);
    st[top] := x;
  end;
function get: longint;
  begin
    get := st[top];
  end;
procedure process;
  begin
    top :=0 ;
    for i:=1 to n do
      begin
        while (top<>0) and (a[get]>=a[i]) do dec(top);
        if top=0 then l[i] := 0 else l[i] := get;
        push(i);
      end;
    top := 0;
    for i:=n downto 1 do
      begin
        while (top<>0) and (a[get]>=a[i]) do dec(top);
        if top=0 then r[i]:=n+1 else r[i] := get;
        push(i);
      end;
    for i:=1 to n do
      if r[i]-l[i]-1>=a[i] then
        res := max(res, a[i]);
end;
procedure print;
  begin
    assign(output,fo);rewrite(output);
    writeln(res);
  end;
begin
  enter;
  process;
  print;
end.

uses math; const fi=''; fo=''; maxn=trunc(1e6)+3; var st : array[1..maxn] of longint; a,l,r : array[1..maxn] of longint; i,j,n : longint; res : int64; top : longint; procedure enter; begin assign(input,fi);reset(input); readln(n); for i:=1 to n do read(a[i]); end; procedure push(x : longint); begin inc(top); st[top] := x; end; function get: longint; begin get := st[top]; end; procedure process; begin top :=0 ; for i:=1 to n do begin while (top<>0) and (a[get]>=a[i]) do dec(top); if top=0 then l[i] := 0 else l[i] := get; push(i); end; top := 0; for i:=n downto 1 do begin while (top<>0) and (a[get]>=a[i]) do dec(top); if top=0 then r[i]:=n+1 else r[i] := get; push(i); end; for i:=1 to n do if r[i]-l[i]-1>=a[i] then res := max(res, a[i]); end; procedure print; begin assign(output,fo);rewrite(output); writeln(res); end; begin enter; process; print; end.