10235 - Simply Emirp

[linux]

Notice

Emirp is a prime number that produces different prime number when reversed not the same.

Okay?

Hope this helps! Keep posting.

[razor_blue]

Thank you linux, your clue is very helpful...

[KaDeG]

Here:

Code: Select all

 if(b==d && prime(b)==b)printf("%d is prime.\n",b);
else if(prime(b)==b && prime(d)==d)printf("%d is emirp.\n",b);
else if(prime(b)==b || prime(d)==d)printf("%d is prime.\n",b);
else printf("%d is not prime.\n",b);

I don't think you need to check if b==d , also see if (prime(b)==0 not b.
(If i get right when prime(n)==0 then n=0)
Do this:
if(prime(b)!=0) -> No prime
else if(prime(b)==0 && prime(d)!=0) -> Is prime
else -> Is emirp
I don't think you need long int, i use simple int and got AC

[bishop]

i tried but

WA
if anyone check why
this is
WA

[Jan]

Check the following line.

Code: Select all

else if(prime(n) || prime(rev))

29 is a prime, isn't it?

[bishop]

only if reverse number is prime
result is not prime
i got it

thanx
a lot

[Bad Boy]

Why it is wrong,

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Hmmmmmmm, AC


[Jan]

2, 3, 5, 7, 11 ... these are primes, not emirps. Read the description again to find the reason.

[apurba]

i am not finding the reason of getting wa??????/
some one please help..............
here is my code................

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/*****  simply emirp @ 10235  *****/



#include<stdio.h>

#include<math.h>



long isPrime(long p)

{

   long s;

   s=long(sqrt(p));

   //if(p==1) return 1;

    //if(p==2) return 1;

    if(p%2==0) return 0;

    for(long i=3;i<=s+1;i+=2)

        if(p%i==0)

         return 0;

   return 1;

}



long RevisPrime(long q)

{

   long r;

   long val=0;

   for(;q;q/=10)

      val = val*10 + q%10;

   r=long(sqrt(val));

   //if(val==1)   return 1;

   //if(val==2)   return 1;

   if(val%2==0)   return 0;

   for(long k=3;k<=r+1;k+=2)

      if(val%k==0)

         return 0;

   return 1;

}



int main()

{

   long num;

   long t1,t2;

   while(scanf("%ld",&num)==1)

   {

      t1=isPrime(num);

      t2=RevisPrime(num);

      if(num==2||num==3||num==5||num==7||num==11)

         printf("%ld is prime.\n",num);

      

      else if(t1==0)

         printf("%ld is not prime.\n",num);



      else if(t1==1 && t2==1)

         printf("%ld is emirp.\n",num);



      else if(t1==1 && t2==0)

         printf("%ld is prime.\n",num);

   }

   return 0;

}



thanks in advance

[amr saqr]

I don't know why am i getting WA too,
I think i read the problem description very carefully

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Removed After AC

[mf]

You forgot to write a terminating \0 to string in this part of your code:

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         int index=0,temp=number;
         while (temp!=0)
         {
            n[index]=temp%10+'0';
            temp/=10;
            index++;
         }
         int t=atoi(n);

[amr saqr]

Thanx so much (mf)
i modified my code and got AC

[pok]

why i got WA ?
i cant understand..
pls someone help me..
pls pls..

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AC..
removed after AC..


[asif_khan_ak_07]

Can anyone point out the mistake in my program...

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#include<stdio.h>
#include<stdlib.h>
#include<string.h>

#define max 1000000

bool pr[max+1];
int prime[max];

int main()
{
   
   long int ns,re;
   int len,r,fg;
   char in[10],rev[10];

   //generating primes

   pr[0]=true;
   pr[1]=true;

   for(int i=2;i*i<=max;i++)
   {
         if(pr[i]==true)
            continue;
      for(int j=i+i;j<=max;j=j+i)
         pr[j]=true;
      //generating ends;
   }
   //program starts

   while(gets(in))
   {
      ns=atol(in);
      if(pr[ns]==true)
      {
         printf("%ld is not prime.\n",ns);
         continue;
      }
      else
      {
         len=strlen(in);
         r=0;
         fg=1;

         for(int k=len-1;k>=0;k--)
         {
            if(in[k]!='0')
               rev[r++]=in[k];
         }
            
         rev[r]='\0';

         re=atol(rev);
         //printf("%ld",re);

         if(pr[re]==false && re!=ns)
            fg++;
      }

      if(fg==1)
         printf("%ld is prime.\n",ns);
      else if(fg==2)
         printf("%ld is emirp.\n",ns);
   
   }


return 0;
}

Thanks in advnce

[tanvirfromhell]

What's wrong with my code?!! I checked every sample output from this post & my code generate correct ans. but got WA in uva. plz help me.

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#include<stdio.h>
#include<math.h>
int main()
{
   long int n,n1,rs;
   int i,j,r;
   bool chk,chk2;
    while(scanf("%ld",&n)!=EOF)
    {
        chk=true;
        if(n==0 || n==1)
            chk=false;
        for(i=2;i<sqrt(n);i++)
            if(n%i==0)
                chk=false;

        if(chk==false)
            printf("%ld is not prime.\n",n);
        else
        {
            chk2=true;
            rs=0;
            n1=n;
            while(n!=0)
            {
                r=n%10;
                rs=rs*10+r;
                n=n/10;
            }
            for(j=2;j<sqrt(rs);j++)
                if(rs%j==0)
                    chk2=false;
            if(rs==n1)
                printf("%ld is prime.\n",n1);
            else if(chk2==true)
                printf("%ld is emirp.\n",n1);
            else if(chk==true)
                printf("%ld is prime.\n",n1);
        }
    }
    return 0;
}


plz...............