ac1156.pas

来自「某牛人写的acm.tongji.edu.cn上大部分ac的代码,仅供学习研究,请」· PAS 代码 · 共 36 行

program tju1156;
const
  divisor=2005;
var
  a,b:array[1..3]of word;
  p,n,t:longint;
procedure merge(x,y,z:byte);
  begin
    t:=b[x]*b[y] mod divisor;
    a[z]:=(a[x]*a[y]+(p-1)*t) mod divisor;
    b[z]:=(a[x]*b[y]+b[x]*a[y]+(p-2)*t) mod divisor;
  end;
procedure cal(x,y:longint);
  begin
    if x=1 then begin
      a[y]:=0;b[y]:=1;
    end
    else if odd(x) then begin
      cal(x shr 1,y);
      merge(y,y,5-y);
      merge(5-y,1,y);
    end
    else begin
      cal(x shr 1,5-y);
      merge(5-y,5-y,y);
    end;
  end;
begin
  a[1]:=0;b[1]:=1;
  repeat
    read(p,n);
    cal(n,3);
    writeln(a[3]);
  until seekeof;
end.