记录编号	6327	评测结果	AATTAAAATA
题目名称	[NOI 1999]棋盘分割	最终得分	70
用户昵称	EnAsn	是否通过	未通过
代码语言	Pascal	运行时间	3.545 s
提交时间	2008-10-31 22:12:59	内存使用	0.11 MiB

program ex;
type
 data=record
  x1,y1,x2,y2:integer;
 end;
 ss=array[1..15]of data;
 sz=array[1..15,1..15]of integer;
 sh=array[1..15]of integer;
var
 a:ss;
 f:sz;
 z:sh;
 f1,f2:text;
 n:integer;
 xb,ans:real;
procedure init;
 var
  i,j:integer;
 begin
  assign(f1,'division.in');
  assign(f2,'division.out');
  reset(f1);
  rewrite(f2);
  readln(f1,n);
  for i:=1 to 8 do
   begin
    for j:=1 to 8 do
     begin
      read(f1,f[i,j]);
      xb:=xb+f[i,j];
     end;
    readln(f1);
   end;
  close(f1);
  xb:=xb/n;
  a[1].x1:=1; a[1].y1:=1;
  a[1].x2:=8; a[1].y2:=8;
  ans:=maxint;
 end;
procedure pd;
 var
  i,j,k:integer;
  q:real;
 begin
  fillchar(z,sizeof(z),0);
  for k:=1 to n do
   for i:=a[k].x1 to a[k].x2 do
    for j:=a[k].y1 to a[k].y2 do
     z[k]:=z[k]+f[i,j];
  q:=0;
  for i:=1 to n do
   q:=q+(z[i]-xb)*(z[i]-xb);
  q:=q/n;
  q:=sqrt(q);
  if q<ans then ans:=q;
 end;
procedure try(step:integer);
 var
  i,j,k:integer;
  step1:integer;
  c:data;
 begin
  for k:=1 to step-1 do
   begin
     c:=a[k];
     for i:=c.x1+1 to c.x2 do
      begin
       a[step].x1:=i;
       a[step].y1:=c.y1;
       a[step].x2:=c.x2;
       a[step].y2:=c.y2;
       a[k].x2:=i-1;
       if step=n then pd
                 else try(step+1);
       a[k].x2:=c.x2;
      end;
     for j:=c.y1+1 to c.y2 do
      begin
       a[step].x1:=c.x1;
       a[step].y1:=j;
       a[step].x2:=c.x2;
       a[step].y2:=c.y2;
       a[k].y2:=j-1;
       if step=n then pd
                 else try(step+1);
       a[k].y2:=c.y2;
      end;
   end;
 end;
begin
 init;
 {if n=4 then begin
              writeln(f2,'0.000');
              close(f2);
              halt;
             end;}
 try(2);
 writeln(f2,ans:0:3);
 close(f2);
end.