NOT A BLOG | sqybi

SGU 181 — X-Sequence

Posted on 五月 25th, 2008.

其实真的不难…自己找一下规律吧.
因为有mod m嘛…然后就几个一循环而已…

{
SGU 181; X-Sequence
- sqybi’s code
}
//for my winsty
program sgu181_sqybi;
  const
    mm = 1000;

  var
    n, i: longint;
    x, a, b, c, m, stop, r: int64;
    f, t: array[0..mm]of longint;

  begin
    readln(x, a, b, c, m, n);
    if n = 0 then begin
      writeln(x);
      halt;
    end;
    fillchar(f, sizeof(f), 0);
    stop := 0;
    for i:=1 to n do begin
      x := (a * x * x + b * x + c) mod m;
      if f[x] = 0 then begin
        f[x] := i;
        t[i] := x;
      end
      else begin
        stop := i;
        break;
      end;
    end;
    if stop = 0 then
      writeln(x)
    else begin
      dec(stop);
      r := (n - (f[x] - 1)) mod (stop - (f[x] - 1));
      if r = 0 then r := stop - (f[x] - 1);
      r := f[x] - 1 + r;
      writeln(t[r]);
    end;
  end.

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