Is my greedy algo correct?
On each step I choose an edge to vertex with the greatest out-degree.
I have WA 8.

I know AC solution that counts number of cw and ccw moves from point i to i+1 seen from the first point. Here is the test on which this AC solution answers cw but correct answer is ccw.

17
0 0
10 0
10 10
11 10
11 9
11 8
11 7
11 6
11 5
11 4
11 3
11 2
11 1
11 0
12 0
12 11
0 11

I don't understand this problem. As I think, the third sample is the tree from the picture. But I can not understand why, for example, 'the number of the ancestor of this node' for the node #18 is 12? What does it mean, 'the number of the ancestor of this node'?

THank you.

small a,
big b,
big n,
and the LCM of a and b is larger than n.
such as
3 24999998 25000000


Edited by author 21.03.2010 23:41

I have written 2 programs and both get WA19
It is very strange, I am already tired to write programs to this problem.

first      2*BFS
secondar   Dijkvasta+Heap
both got Wa19 i not understand why.
Somebody help me?

there is my program


var
c:array[0..1800] of real;
n,m,i ,fn:longint;
begin
readln(n,m);
c[0]:=1;
c[1]:=m-1;
i:=1;
repeat
i:=i+1;
{for i:=2 to n do   }
c[i]:=(m-1)*(c[i-1]+c[i-2]);
until i>=n;
writeln(c[n]:0:0);
end.

My AC program runs about 10 seconds on following tests;

4 41
4 49 (on this test it works more, that 1 minute!!!)
17 43
19 49
41 43
50 41
50 43

I can write about 10 more tests, but, I think, it's enough:)
Could you add some of these tests?

Here is my code, what can make my code run faster? Please check it up...

#include <iostream>
#include <cmath>
using namespace std;
bool prime(long long x)
{
    int i;

    if(x==2)
       return true;
    else if(x%2==0)
       return false;

    for(i=3; i*i<=x; i+=2)
        if(x%i==0)
           return false;
    return true;

}
int main()
{
    long long K, s;

    cin>>K;
    if(prime(K)==true)
    {
        cout<<K-1;
        return 0;
    }
    else
    {
        for(long long i=3; i<499999950; i++)
        {
            if(K%i==0)
            {
                cout<<i-1;
                return 0;
            }
        }
    }
    return 0;
}

Hope this test can help you:

2
3
2 1 0
1
0
-
NO
YES

Good luck!

why my program doesnot work on WA#2????
var a:array [1..10000] of integer;
i,k,s:integer;
begin
k:=0;
s:=1;
for i:=1 to 10 do
readln(a[i]);
for i:=1 to 10 do
s:=s*a[i];
for i:=1 to s do
if s mod i=0 then
k:=k+1;
if (k>0)and (k<10) then writeln(k);
end.

Edited by author 21.03.2010 05:16

I can't find a mistake in my solution. Can anybody give me any hint?

#include <cstdlib>
#include <iostream>
#include <iomanip>

using namespace std;

int main(int argc, char *argv[])
{

    double a,b,c,d,m,n=2,mn;
    cin>>a>>b;
    c=a/100;
    d=b/100;
    while (1)
    {m=1;
     while (m<n)
    {mn=m/n;
     if ((mn<d)&&(mn>c)) break;
     m++;}
     if (m!=n) break;
     n++;}
     cout<<n<<endl;
    system("PAUSE");
    return EXIT_SUCCESS;
}




This is my project Got WA on test14.
I think there's something wrong with digits
But i cannot find it
Can anyone help me with it?
Thx!

  I used "dp"  and spend 261k space and 0.046 time,

  but i see the rank 1 only used 0.015 second?

            How did he make it?

Does it mean that we need to calculate the maximal displacement where the center goes even when it falls? And after the book starts falling must we consider that the book just rotates around the edge of the bookshelf? or it slides a little backwards. Some more explanation of the problem text and maybe some hints would be welcomed. Thank you.

L.E. Now I get WA 8. I don't think there is a problem with precision, or something like that. Some more samples to pass this test? Does L have to be used at anything? I believe not since L>H.

L.L.E. My WA 8 was from a division by 2 of an integer variable, which I  assigned to a double variable. The problem was solved when I divided by 2.0

Edited by author 25.03.2010 20:20

#include<iostream>
#include<algorithm>
#include <list>
#include <math.h>
#include <iomanip>
using namespace std;
/*CODE*/

int main()
{
   /*CODE*/
    cout<<setprecision(9)<<fixed<</*CODE*/
    <<sqrt(r2);
return 0;
}

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;
}

Give it me, please :(

Submitting one problem I had a compilation error with making my own set comparator, although the program had succesfully been compiled by G++(GCC) 4.4.3 and Visual Studio 2008 compilers on my computer. By submitting some test programs I've found that the error is somehow related to the lower/upper_bound method of map and set containers. For instance, the code like this gets a compilation:

#include <set>
using namespace std;

struct Less
{
bool operator()(pair <int,int> a, pair <int,int> b)
  { return a.first < b.first; }
};

set <pair <int,int> , Less> s;
set <pair <int,int>, Less>::iterator it;

int main()
{
        s.insert(make_pair(1,1));
    it = s.lower_bound(make_pair(0,1));
    return 0;
}


The error message is following:

5bf1d001-ac4d-4354-a106-244d4befaf4e
S:\checker\compile\\Vc7\include\xtree(988): error: no instance of function "Less::operator()" matches the argument list and object (the object has cv-qualifiers that prevent a match)
            argument types are: (const std::pair<int, int>, const std::_Tree<std::_Tset_traits<std::pair<int, int>, Less, std::allocator<std::pair<int, int>>, false>>::key_type)
            object type is: const Less
              if (this->comp(_Key(_Pnode), _Keyval))

                  ^
          detected during:
            instantiation of "std::_Tree<_Traits>::_Nodeptr std::_Tree<_Traits>::_Lbound(const std::_Tree<_Traits>::key_type &) const [with _Traits=std::_Tset_traits<std::pair<int, int>, Less, std::allocator<std::pair<int, int>>, false>]" at line 801
            instantiation of "std::_Tree<_Traits>::iterator std::_Tree<_Traits>::lower_bound(const std::_Tree<_Traits>::key_type &) [with _Traits=std::_Tset_traits<std::pair<int, int>, Less, std::allocator<std::pair<int, int>>, false>]" at line 21 of "5bf1d001-ac4d-4354-a106-244d4befaf4e"

compilation aborted for 5bf1d001-ac4d-4354-a106-244d4befaf4e (code 2)


So I think that it makes some STL features unavailable and wish it to be fixed.

Does anybody know what can this test contain? I get WA every time I send my solution, can anybody give me some advice? If you need my code, you can connect me on the ICQ (425805594)