OJ Board

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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;

}

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Removed After AC

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AC..
removed after AC..

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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;
}

Code: Select all

#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;
}

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#include<stdio.h>
static char sieve[1000001];
unsigned long reverse(unsigned long x)
{
         unsigned long r=0;
         do
         {
                  r=r*10+(x%10);
                  x/=10;
         }while(x);
         return r;
}
         
int main()
{
    unsigned long int i,j,n;
    sieve[0]=sieve[1]=0;
    for(i=2; i<100001; i++) sieve[i]=1;
    for(i=2; i<1001; i++)
    {
             if(sieve[i]!=0)
             {
                              for(j=i+1; j<1000001; j++)
                              {
                                         if (sieve[j]!=0)
                                         {
                                                           if((j%i)==0) sieve[j]=0;
                                         }
                              }
             }
    }
    while(scanf("%lu",&n)!=EOF)
    {
                               if(sieve[n]==0) printf("%lu is not prime.\n",n);
                               else if(sieve[n]==1)
                               {
                                    if((sieve[reverse(n)]==1) && (n!=reverse(n))) printf("%lu is emirp.\n",n);
                                    else printf("%lu is prime.\n",n);
                               }
    }
    return 0;
}  

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/* Removed */