Prime Palindromes

Why cant  I view the problem ??

There is something wrong with the test cases. This will be fixed in a few days.

M is less than or equal to N. I had to find that out by trial-and-error. Why doesn't your software permit you to enter numeric symbols? Since most of the problems are numeric in nature, this is quite a handicap. I notice you have fixed some of them, though. Thank you.

how to remove the time limit exceeded error in this program.............

You must find the smallest integer M N such that M is a prime number and M is a palindrome.

can u please explain the meaning of underlined text ! ! !

i.e how M is realted to N ? ? ? ?

It should say M >= N, as John pointed out in the comment 2 above yours.

yeah. . i got it. . .nyways thnx fr replyin Stephen ! !  !

@Stephen

It should say M >= N to be coherent with the example.

Whoops, thanks. Fixed.

@ALL

anytest case/s which takes time??

Hey all,

My program is running for small test cases but as the value is increased it is unable to show the result.The best that it went upto was around 98000.Someone please rectify the mistake.

Here's the code...

#include<stdio.h>

int main()

{

unsigned long int n,rev,i,j,k,m=0;

unsigned long int fl=1;

rev=0;

printf("Enter the number:");

scanf("%d",&n);

for(i=n;;i++)

{

fl=1;

for(j=2;j<i/2;j++)

{

if(i%j==0)

{

fl=0;

}

}

if(fl==1)

{

m=i;

while(m>0)

{

k=m%10;

rev=(rev*10)+k;

m/=10;

}

if(rev==i)

{

break;

}

else

rev=0;

}

}

printf("The required number is: %d",rev);

return 0;

}

@admin............plz check the sol

http://www.codechef.com/viewsolution/246369

i m getting TLE ........but it is working fine on my system

HELP HELP HELP

@Admin:

I've tried a lot to reduce the time, I've managed to reduce the time to check if the number is prime to a bre minimum, I've taken tth least time to compute if its a palindrome or not. Can you please tell me which part is taking time, because I've tried tor educe all parts. My code:

http://www.codechef.com/viewsolution/247098

Thank you.

@vikas - your code doesn't work for the sample input.

@Manjot - try input 99000.

i removed that error........and also tried to optimise the code to a great extent............then also i am getting TLE.......plz tell me .........where my code is lacking ..........plz help me.......this is optimised one.....

http://www.codechef.com/viewsolution/247548 plz check it..........

sir..plz check my solution.........and tell me the bug in  solution,,,,,,,,,,http://www.codechef.com/viewsolution/247548

http://www.codechef.com/viewsolution/247548

@admin -> its really frustrating...........so many TLEs.......

may i know that....which part of my code or for which input case my code is taking such a long time???????

any hint ??????????????

my code->http://www.codechef.com/viewsolution/268644

thank you.............

i was doing the stupid mistake........but finally goi it accepted...........

thnx for not answering my questions...........

Can anyone tell what must be the output for 99000.....

@Anish 1003001 is the output for 99000

@Piyush:- Yep got it... Thanks man....

Hello admin,

I'm not understanding why I'm getting the wrong answer, I have checked for the boundary numbers too.

What about single digit prime number? Please reply , where my code is giving the wrong answer.

please give me a hint atleast, as it is not a contest problem now.

Thanks...

I got it correct....

But before, I was using sieve of Erathmosis method to generate prime upto 1000000 and then storing the palindromes in an array. This was giving me a SIGGEV error.

Then I just changed the code that had only the valid prime palindromes.. and this worked ... But I didn't get why the previous code was giving that particular error ????

Thanks

what will be the output if number is greater then 98689

what should be prined after 98689 because the answer is 1003001 which is less tha 1000000.....

pls reply.....

thanx.

The problem statement just says N is less than a million, it doesn't say your answer must be.

please check my code why it is giving wrong answer

http://www.codechef.com/viewsolution/301604

thanx ...

I m nt able to submit my code.....Its showing "Wrong Login & Password"

can any one please tell me where i am going wrong

http://www.codechef.com/viewsolution/301604

please reply....

Whats wrong with my code can any one tell me please i submitted lot of solution...

http://www.codechef.com/viewsolution/317757

please help...

Hello Admin,

I am getting Runtime Error.But am not able to find out why.!

I take input in a string type and first check for palindrome then check if that palindrome is a prime or not.

Please help.!

My code is:

#include<iostream>

#include<math.h>

#include<string>

using namespace std;

string s;int c=9;string str;

int palindrome()

{

int k=0;int count=0;

while(1)

{

if(s[count]=='0')

count++;

else

break;

}

int i=count;//cout<<"count"<<(31-count)/2+count;

while(i<=((c-count)/2+count))

{

if(s[i]!=s[c-i+count])

{

k=1;

break;

}

i++;

}

if(k==1)

{return 1;}

else

return 0;

}

int increment()

{

if(s[c]=='9')

{

s[c]='0';c--;

increment();

}

else

{

s[c]=(char)((int)s[c]+1);//cout<<"h";//cout<<s[c];

return 0;

}

}

int prime()

{

int k=0;int count=0;

while(1)

{

if(s[count]=='0')

count++;

else

break;

}

int i=count;

int number=0;

//cout<<"count="<<count;

while(i<=c)

{

number=number*10+ (((int)s[i])-48);

i++;

}

int g=0;

int root=pow(number,0.5);

for(int ii=2;ii<root;ii++)

{

if(number%ii==0)

{

g=1;break;

}

}

if(g==1)

return 0;

else return number;

}

int main()

{

cin>>str;int m=str.length()-1;int i=c;

//cout<<c;

for( i=c;i>c-str.length();i--)

{s[i]=str[m];m--;}

for(;i>=0;i--)

s[i]='0';

while(1)

{

int chk=palindrome();

if(chk==0)//palindrome

{

int p=prime();

if(p!=0)

{

cout<<p;

break;//found the prime

}

}

int tt=increment();c=9;

}

system("pause");

return 0;

}

I got it!Thanks!

1s for this problem is calculated for single N or running the code several times for different N's?

This is explained in the FAQ. In this case, each input file only contains one N, so the time limit only applies to that one N.

I am getting a runtime(other) error.According to the FAQ it is generally caused by using too much memory. But I don't think that's the problem this time around. Its giving the correct answer for all test cases that I checked on my machine.

Please take a look and point out the mistake

http://www.codechef.com/viewsolution/398600

hello admin plz check my code plz

#include<stdio.h>

# define max 1000000

int main()

{

int n,i,num,temp,count=0,j,remainder=0,sum=0;

printf("enter initial limit:");

scanf("%d",&n);

for(i=n;i<max;i++)

{

num=temp=i;

while(num>0)

{

remainder=num%10;

num=num/10;

sum=sum*10+remainder;

}

if(sum==temp)

{

for(j=2;j<temp;j++)

{

if(temp%j==0)

count=1;

}

if(!count)

{

printf("%dn",temp);

break;

}

}

sum=0;

count=0;

}

return 0;

}

it is finely working.plz help i can't figure out what is  the problem in this code.codechef compiler is giving wrong answer

Please read the FAQ.

/sources/tested.c: In function 'main': /sources/tested.c:7: error: expected ')' before ';' token

WTF....?

what is the problem in my program?

and after correction it is showing time limit exceed......

can nebody tell wats wrong with my program? a runtime error is encountered.

#include<stdio.h>
#include<math.h>
//#include<conio.h>
int prime(long int num)
{
int i;
if(num==2) return(1);
else if(num%2==0) return(0);
else
{for(i=3;i<(sqrt(num));i=i+2)
{
if(!(num%i))
return(0);
}
return(1);}
}
int palin(long int rev,long int num)
{
long int temp=num;
while(num>0)
{rev=(rev*10)+(num%10);
num=num/10;}
if(temp==rev)
return(1);
else
return(0);
}

void main()
{
int pc,pac=0,rev=0;
long int num;
scanf("%ld",&num);
while(!pac)
{
pc=prime(num);
if(pc)
{pac=palin(rev,num);
if(pac)
printf("%ld",num);
}
num+=1;
}
//getch();
}

plz help me . y this code is printing garbage value in TURBOC

int main()

{

unsigned long int i=1000000;

printf("nnnn  hello =%ld",i);

return 0;

}

@Raman Tripathi the format specifier '%ld' is wrong, chk the link. '%ld' is for signed long integer and not for unsigned.

There's no max limit specified in problem, but from (1 N 1000000) we assume that max limit is 1000000, but answers will be tested beyond this case.

I've also found a list of Palindromic Primes, you can check your answers are correct or not from here:

http://oeis.org/A002385/b002385.txt

Hey all,

My program is running for small test cases but as the value is increased it is unable to show the result.The best that it went upto was around 98000.Someone please rectify the mistake.

Here's the code...

#include<cstdio>

#include<iostream>

using namespace std;

int main()

{unsigned int flag=1,num,digit;

unsigned int n,b;

cin>>b;

for(unsigned int i=b;i<1000000;i++)

{

flag=1;

for(unsigned int j=2;j<i;j++)

{

if(i%j==0)

{

flag=0;

break;

}

} if(flag==1)

{

// cout << i << " ";

num=i;

n=i;

unsigned int rev=0;

do{

digit=num%10;

rev=rev*10+digit;

num=num/10;

}while(num!=0);

if(n==rev)

{cout<<n<<" ";break;}

}

}   system("pause");

return 0;

}