10036 - Divisibility

[titid_gede]

How to avoid time limit exceeded for this problem?

with love & light,

titid

[turuthok]

Dynamic Programming, tid ...

Start from the leftmost. Perform both addition and subtraction with the next integer and get the modulus ... The result will be between 0 -> k-1. Create a flag-array to mark that this position is valid.

In the next iteration, use that flag-array and for every valid position, perform both addition and subtraction like before with the next integer. And don't forget to get the modulus ... use another flag-array and mark the valid positions.

Do it repeatedly and when the last flag-array has its first element marked valid, that means it is divisible.

-turuthok-

[erfan]

It is DP problem.

such input of data is in p[]; divident is k;
Firstly s=p[0]%k;store it in two dimensional array in a[0][s]=1.
Then s=s+p[1]%k,a[1][s]=1 & s=s-p[1]%k,a[1][s]=1 in this way proceed
until end of p[];In last if a[last][0] is 1 then divisible else not.
I think you can realize.

[SilVer DirectXer]

[cpp]
#include <iostream>
#include <math.h>
using namespace std;
int n,k,i,j,l;
int input[10005];
int oper[10005];
int apv;
int sum;
int carry;
int ncase;
int ok;

void main(void)
{
cin>>ncase;
for (l=1;l<=ncase;l++)
{
for (i=1;i<=10001;i++)
oper=0;

apv=0;

cin>>n>>k;

for (i=1;i<=n;i++)
{
cin>>input;
apv+=input;
}

ok=0;
for (j=1;j<=(int)pow((int)2,(int)(n-1));j++)
{
carry=0;
oper[n-1]++;

for (i=n-1;i>=1;i--)
{
oper+=carry;
if (oper==2)
{
carry=1;
oper=0;
}
else
{
carry=0;
}
}
sum=apv;
for (i=1;i<=n-1;i++)
{
if (oper==1)
{
sum-=2*input[i+1];
}
}
if (sum % k==0 && sum!=0)
{
ok=1;
break;
}
}
if (ok==1)
cout<<"Divisible"<<endl;
else
cout<<"Not divisible"<<endl;
}
}

[/cpp]

i got a WA but i dont know why...pls help ....
and, if the input like this:
1 <---number of case
2 3 <---n and k
1 1
what will be the answer?

[Red Scorpion]

my code gives "Divisible".

[doggn]

#include <iostream>
#include <vector>
#include <math.h>

using namespace std;

int main(void)
{
int CaseNum;
cin >> CaseNum;

for(int i=0;i<CaseNum;i++)
{
int n,k;
cin >> n >> k;
vector< vector<int> > arr;
for(int p=0;p<n;p++)
{
vector<int> temp;
for(int p2=0;p2<k;p2++)
temp.push_back(0);
arr.push_back(temp);
}

vector<int> input;
for(int j=0;j<n;j++)
{
int in;
cin >> in;
if(j==0)
input.push_back(in);
else
input.push_back(abs(in));
}

if(input[0] < 0 )
arr[0][k-(abs(input[0])%k)]=1;
else
arr[0][input[0]%k]=1;

for(int scan=0;scan<n-1;scan++)
{
for(int s=0;s<k;s++)
if(arr[scan][s]==1)
{
int next=scan+1;
int ar=input[next];
arr[next][(s+ar)%k]=1;
arr[next][(s+k-(ar%k)) % k]=1;
}
}
if(arr[n-1][0]==1)
cout << "Divisible";
else
cout << "Not divisible";

if(i<CaseNum-1)
cout << endl;
}
return 0;
}

I got a WA. please help me .....

[Karthekeyan]

Here's my code that gives runtime error - sigsegv....
Can anyone temme why?

Code: Select all

spoiler

thanx in advance for the help!

[dumb dan]

int a[105][105]={0};
...
for(int i=1;i<N;i++)
...
a[temp]=1;

N might be much larger than 105

[Karthekeyan]

u r rite "dan"....
but i changed

a[105][105]

to

a[10001][105]

and now I get WA......ne reasons?

[dumb dan]

this input:

Code: Select all

1
4 9
8 2 3 4

should yield this output:

Code: Select all

Divisible

since 8+2+3-4=9

[Karthekeyan]

here's the changed code....
see the change done in the code...

Code: Select all

removed after getting ac

[qndel]

I solved this problem using simply DP but i'm not satisified with my time( over 2 seconds). I would be vary happy if anybody would tell me some faster algorithm.

[I LIKE GN]

i amm getting WA
Need some IO...
please help

[tan_Yui]

Hi, 'Karthekeyan', 'I LIKE GN'.
Karthekeyan, your code should consider about minus by getting absolute value.

In this case :
5 15
-1 -2 -3 -4 -5
-1 + -2 + -3 + -4 + -5 = -15 (-15 is divisible by 15)

Input :

7
4 7
17 5 -21 15
4 5
17 5 -21 15
10 30
9 -97 3 5 -1 0 11 -46 19 17
10 97
9 -97 3 5 -1 0 11 -46 19 17
12 16
-11 7 -73 40 5 -2 66 21 -64 16 16 16
5 15
-1 -2 -3 -4 -5
5 9
-5 -4 2 -2 0

Output should be :

Divisible
Not divisible
Divisible
Not divisible
Not divisible
Divisible
Divisible

Best regards.

[I LIKE GN]

hello
thx for reply
i checked all ur i/o..
they are ok...
one thing
i made a random huge file with several test cases where
the inputs were like
10000 41
10000 randomly generated numbers...
10000 93
...
...
the most suspectable matter is my program gives
"Divisible" for ALL inputs...
so perhaps i amm missing something and
also i don know how to post such huge files here(i.e. as a link or
others)
thx.