I checked my program, and I'm pretty sure that it gives the correct answers for the sample input/output, and for all the tests given on this forum. I also went to the page of NEERC 2002 and downloaded their test examples, and everything seems to be correct.

I tried ending output with or without a newline('\n'), and I still can't figure out why I could possibly be getting a wrong answer three times in a row.

Please give me some advice as to where my problem is. Maybe it is someting small? Maybe I misread something in the problem statement?

Anyway, here's my program(I'm sure the code is pretty bad, but keep in mind that I don't have much experience with these sorts of problems):

#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    int A[10002];
    long int pos = 0;

    cin.unsetf(ios::skipws);

    do {
        char input[3];

        cin >> input[0];

        if(input[0] == '\n') break;

        cin >> input[1];

        input[2] = 0;

        A[pos] = (int) strtol(input, (char **) input + 2 * sizeof(char), 16);
        pos++;

    } while(1);

    int current;
    int key;

    char input[3];
    input[0] = 'C';
    input[1] = '9';
    input[2] = 0;

    cin >> input[0] >> input[1];
    key = (int) strtol(input, (char **) input + 2 * sizeof(char), 16);
    key ^= 32;

    for(int i = 0; i < pos; i++) {
            cout << hex << uppercase << setfill('0') << setw(2) << key;

            cin >> input[0] >> input[1];

            current = (int) strtol(input, (char **) input + 2 * sizeof(char), 16);

            key = ((key) ^ (A[i])) ^ (current);
    }

    cout << hex << uppercase << setfill('0') << setw(2) << key << "\n";

    return 0;
}

Please help! Any advice will be appreciated!

Finally I got accepted. I include several tests to help you debug:
input            output:
8                YES
1 70             1 70
4 65             4 65
64 66            61 64
61 64            65 64
66 62            66 64
80 50            66 62
80 60            80 60
65 64            80 50

input:           output:
3                YES
1 3              1 3
2 1              1 2
2 3              3 2

var
  n,i,j,l:integer;
  a:array[1..100,1..100] of integer;
begin
  read(n);
  for i:=1 to n do
    for j:=1 to n do
      read(a[i,j]);
  i:=1;
  j:=1;
  for l:=1 to n do
    begin
      i:=l;
      j:=1;
      while i<>0 do
        begin
          write(a[i,j],' ');
          dec(i);
          inc(j);
        end;
    end;
  for l:=n + 2 to n + n do
    begin
      i:=n;
      j:=l - n;
      while j <= n do
        begin
          write(a[i,j],' ');
          dec(i);
          inc(j);
        end;
    end;
  readln;
  readln;
end.

How can i reach acm.timus team? I tried to write an e-mail, but it returned to me with some errors in their mailing box.

I can`t find place where it can be crash.

If you solve this problem with a help of finding roots of the initial polynom, use long long or __int64 type in this function! This fact costed me about 5 submissions...
This is the part of my code:

long long PolynomValue (vector<int>PolynomCoeffs, int x0)
{
long long value;
...
return value;
}

int FindRoot (vector<int> PolynomCoeffs)
{
...
if (!PolynomValue(PolynomCoeffs,a)) return a;
...
}
If I changed long long to int I would not find a root in several cases.

To understand me more clearly try these tests:

-20000 19998 20000 -19999
(x-1)(x-1)(x+1)(x-19999)

-19998 -20000 20000 -19999
(x-19999)(x3+x2-x+1)

-19999 -19999 -19999 -20000
(x+1)(x-20000)(x2+1)

I guess 13th and 14th tests are something like these ones.
Good luck!

Edited by author 22.01.2010 21:07

Please, give me some difficult tests...

Send them please on snipious@mail.ru!!!

Can anybody tell me how to calucate bynomial coefficients with a help of the fastest method?

uses math;
var len,r:extended;
begin
 read(len,r);
 if(r<=len/2)then writeln((pi*r*r):0:3) else
 if(sqrt(2)*len/2<=r)then writeln((len*len):0:3) else
  writeln((pi*r*r-4*arccos(len/r/2)*r*r+2*len*sqrt(r*r-len*len/4)):0:3);
end.

that is what my AC prog gives on some tests:
n=7, res=1
n=7777, res=2340
n=77777, res=23412
n=99997, res=30101
n=99998, res=30102
n=52251, res=15728
n=55555, res=16723
n=100000, res=30102

var
  a : array[-1000..0] of integer;
  b : array[0..1000] of integer;
  n, i, j, k, l, m, u, x : integer;
  c : array[1..100] of integer;
begin
  read(n, x);
  k := 0;
  m := 0;
  l := 0;
  u := 0;
  j := 0;
  i := 0;
  for i := 1 to n do begin
    read(c[i]);
    if c[i] >= 0 then b[c[i]] := 1 else a[c[i]] := 1;
  end;
  if b[0] = 1 then u := 1;
  if x = 0 then begin
    k := 0;
    m := 0;
  end;
  if x < 0 then begin
    for i := x to -1 do begin
      if a[i] = 1 then begin
        u := 1;
        break;
      end;
    end;
    if i = 0 then begin
      for j := 0 downto x do begin
        inc(m);
      end;
      m := m - 1;
      repeat
        inc(k);
      until b[k] = 1;
      k := 2 * k + m;
      end;
  end;
  if x > 0 then begin
      for i := 0 to x do begin
        if(b[i]) = 1 then begin
          u := 1;
          break;
        end;
      end;
      if i = x + 1 then begin
        for j := 0 to x do begin
          inc(k);
        end;
        k := k - 1;
        repeat
          inc(m);
          dec(l);
        until a[l] = 1;
        m := 2 * m + k
      end;
    end;
    if u = 1 then writeln('Impossible') else
    writeln(k,' ', m);
    readln;
    readln;
end.
my code it is work for different numbers and tests (my tests( but WA 1) plese, who can help me?

I have had WA#3, but when I have tried following test, I pass Test#3, but have WA#13:

4 3 2
2.0 0.0
2.0 10.0

Right answer:
0.0000000

Now I have AC.

Edited by author 20.01.2010 13:32

#include<iostream>
#include<vector>
using namespace std;

#define forr(i,x,y) for(int i=(int)(x); i<=(int)(y); i++)

int p[24][6]={
{1,2,3,4,5,6},{1,2,6,5,3,4},{1,2,4,3,6,5},{1,2,5,6,4,3},{2,1,4,3,5,6},{2,1,6,5,4,3},{2,1,3,4,6,5},{2,1,5,6,3,4},
{3,4,2,1,5,6},{3,4,6,5,2,1},{3,4,1,2,6,5},{3,4,5,6,1,2},{4,3,6,5,1,2},{4,3,2,1,6,5},{4,3,5,6,2,1},{4,3,1,2,5,6},
{5,6,3,4,2,1},{5,6,1,2,3,4},{5,6,4,3,1,2},{5,6,2,1,4,3},{6,5,3,4,1,2},{6,5,2,1,3,4},{6,5,4,3,2,1},{6,5,1,2,4,3}};
int n,a[7],b[7],id[7][7][7][7][7][7],m=0,x=0;
vector< vector<int> > y(100100);

int main() {
 scanf("%d",&n);
 forr(i,1,n) {
  scanf("%d %d %d %d %d %d",&a[3],&a[4],&a[2],&a[5],&a[1],&a[6]);
  forr(q,0,23) if(x=id[a[p[q][0]]][a[p[q][1]]][a[p[q][2]]][a[p[q][3]]][a[p[q][4]]][a[p[q][5]]])break;
  if(!x) { y[++m].push_back(i); id[a[1]][a[2]][a[3]][a[4]][a[5]][a[6]]=m; } else y[x].push_back(i);
 }
 printf("%d\n",m);
 forr(i,1,m) { forr(j,0,y[i].size()-1) printf("%d ",y[i][j]); printf("\n"); }
}

There are three themes about mistake in check system!!! Add tests

http://acm.timus.ru/forum/thread.aspx?space=1&num=1005&id=23613
and
http://acm.timus.ru/forum/thread.aspx?space=1&num=1005&id=22373
and
http://acm.timus.ru/forum/thread.aspx?space=1&num=1005&id=21912

"When no more circles can be inscribed, the distance between the first and the last inscribed circles is measured."

What is the definition of the distance between two circles?

kakoi v etoi zada4i moget bit` podvoh?
u menya na 12 teste valitsa

thanks...
sorry for my bad english

helo!
this is just a suggestion, i believe there should be an option (if they wish) for authors to display their email address to be contacted !
as it will enable and allow for more communications between authors.

my address is, baiguzair@gmail[dot]com