It's interesting that answer approaches to pi number without decimal point. If you'll increase r, answer becomes more and more precisely. For example: answer for r = 1e5 is 31416325412, but for r = 1e9 (although r < 1e5) is 3141592657589764752, when pi equals to 3.141592653
Anybody knows why it's happens?

Edited by author 28.12.2017 02:31

Edited by author 28.12.2017 02:31

https://oeis.org/A281795

Edited by author 29.01.2018 22:10

Give me some test. Or give me test 10!

Edited by author 14.02.2007 18:59

1. Use __int64
2. Here is some fragment of my code(and the most significant):
   for(x=0;x<r;x++)
     k+=ceil(sqrt((double)(r-x)*(r+x))); <----- be careful!!

I cannot pass test10 and i cannot find any mistakes.
Is my algo wrong?
my code:
program p1490;
var
  r,n:int64;
  i:longint;
  x:real;
begin
  readln(r);
  for i:=r-1 downto 0 do
    begin
      x:=sqrt(sqr(r)-sqr(i));
      if x-trunc(x)<1e-10
        then inc(n,r-trunc(x))
        else inc(n,r-trunc(x)-1);
    end;
  writeln(4*(r*r-n));
end.

Ignore statement about 1'000'000 square kilometers or you will get WA9

What's wrong with the test 10?

#include<stdio.h>

int main(){
long unsigned int x,y=0,z=0,q,p,r;

scanf("%lu",&r);

x=r;
q=r*r;

do{
p=q-y*y;
 while( x*x >= p && x >= 0 )x--;
z+=(x+1);
y++;
}while(y<r);

z*=4;
printf("%lu\n",z);

return 0;
}

Сабж. Условие не соответствует решению

I haven't crash on my computer on all tests but have crash floating-point 10... Also my answers r<20000 is right if my brute force is right. sorry for my bad English

I don't understand why WA#4 here is my code(maybe I use uncorrect algo?):
#include<iostream>
#include<cmath>
#include<stdio.h>
using namespace std;
int main()
{
    unsigned __int64 k=0;
    long r;
    cin>>r;
    if(r==1)
    {
        cout<<4<<endl;
        return 0;
    }
    if(r==2)
    {
        cout<<16<<endl;
        return 0;
    }
    k=(r-1)*8;
    k=k+(r-1+r-1)*(r-1+r-1);
    printf("%I64u\n",k);
    return 0;
}

var n,x,r:integer;
    y2,y,s:int64;

BEGIN
s:=0;
read (n);
r:=n;

 for x:=0 to n-1 do
  begin
   y:=trunc(sqrt(r-x)*sqrt(r+x));

     if y*y<>(r-x)*(r+x) then y:=y+1;

    s:=s+y;
  end;

writeln (s*4);
END.

10
344

6
132

666
1396052

100000
31416325412

99999
31415696920

i dont know why i ahve got WA7

Here is my code(pls help me :D)

#include<stdio.h>
#include<math.h>

long i, j, r;
unsigned long nr;

int main()
{
    scanf("%ld", &r);

    for(i = 1; i <= r; i++)
        for(j = 1; j <= r; j++)
            if((double)(sqrt(i * i + j * j) - r) >= sqrt(2))
                nr++;

    nr = r * r * 4 - nr * 4;

    printf("%ld\n", nr);

    return 0;
}

Edited by author 25.09.2008 14:42

Help me!
Program Contest_B;
Var
  I, R : LongInt;
  Ans : Int64;
  Tmp : Extended;
Begin
  ReadLn(R);
  If R = 1 Then
    Ans := 4
  Else
    Begin
      Ans := 0;
      For I := R - 1 Downto 0 Do Begin
        Tmp := Sqrt(Sqr(R) - Sqr(I));
        If Tmp - Trunc(Tmp) <= 1E-9 Then
          Inc(Ans, Trunc(Tmp))
        Else
          Inc(Ans, Trunc(Tmp) + 1);
      End;
      Ans := Ans * 4;
    End;
  WriteLn(Ans);
End.

Why i get WA on test 5? This is my solution:

var r,sum,n:extended;
begin
readln(input,r);
sum:=4*sqr(r);
n:=int((sqrt(2)-1)*r/sqrt(2));
write(output,(sum-2*n*(n+1)):0:0);
end.

Edited by author 24.05.2007 21:21

I pass all tests that were mentioned in this thread but I get WA 5, can someone who has fixed such bug tell me what's special in this test ? Btw, just to add I use bruteforce in order to precalc, but I had mistaken the data type and used long instead of unsigned long long , so I've already fixed this bug :)

Edited by author 31.10.2006 17:37

Если площадь квадрата ограничена 1000000, то максимальная площадь поражения и будет 1000000, сторона зала - не более 1000 метров, круг обрезается по четырём сторонам, если радиус превышает 500.