10235 - Simply Emirp

[brianfry713]

An Emirp (Prime spelt backwards) is a Prime that gives you a different Prime when its digits are reversed.

[jokerz]

Yeah i know that.i checked my code with different output but i didn't find any mistake..i submitted it but i was getting wa wa ..if u have time kindly run my code and inform me about my fault.....thank you brianfry713

[brianfry713]

727 is prime.

[jokerz]

Thnx brianfry713...i have gotten AC with the help of your clue...Thnx again..

[mujtahid.akon]

here is my code.
why am i getting WA???
please help ..

http://pastebin.com/X1vPYQJs

[brianfry713]

http://acm.uva.es/board/viewtopic.php?t=76675

[uDebug]

An Emirp (Prime spelt backwards) is a Prime that gives you a different Prime when its digits are reversed.

Phew! Thanks so much for this and for the test case. I totally missed this while reading the problem statement.

[uDebug]

Here's some input / output I found useful during testing / debugging.

Input:

Code: Select all

999
481184
373
998001
998857
753257
823455
999999
850058
78887
999983

AC Output:

Code: Select all

999 is not prime.
481184 is not prime.
373 is prime.
998001 is not prime.
998857 is emirp.
753257 is prime.
823455 is not prime.
999999 is not prime.
850058 is not prime.
78887 is prime.
999983 is emirp.

[woaraka92]

whats wrong with this code??

#include<stdio.h>
#include<math.h>

int prime(long int n)
{
long int i;
if(n==0)
return 0;
for(i=2;i<=sqrt(n);i++)
{
if(n%i==0)
return 0;
}
return 1;
}


long int rev(long int n)
{
long int s=0;
while(n!=0)
{
s=s*10+n%10;
n/=10;
}
return s;
}


int main()
{
long int n,r;
while(scanf("%ld",&n)==1)
{
if(prime(n)==0)
printf("%ld is not prime.\n",n);
else
{
r=rev(n);
if(prime(r)==0)
printf("%ld is prime.\n",n);
else
printf("%ld is emirp.\n",n);
}
}
return 0;
}

[lighted]

An Emirp (Prime spelt backwards) is a Prime that gives you a different Prime when its digits are reversed

So must check if r not equal to n to be "emirp"

Code: Select all

if(prime(r)==0 || r == n)
 printf("%ld is prime.\n",n);

Don't forget to remove your code after getting accepted.

[ashek.rahman]

Accepted Removed
Thanks for your help

[lighted]

Your code doesn't pass all tests posted in this thread.

101 is prime, not emirp, it has to be a different prime after reversal.

Don't forget to remove your code after getting accepted.

[DarkknightRHZ]

Hi, can anyone please help me with this code. I have checked everything but still wrong answer!

Code: Select all

#include <bits/stdc++.h>

using namespace std;

#define PB          push_back
#define PF          push_front
#define  V          vector
#define PII         pair <int,int>
#define MII         map <int,int>
#define MSI         map <string,int>
#define MIS         map <int,string>
#define MLI         map <long long int,int>
#define MIL         map <int,long long int>
typedef long long int           LL;
typedef int                     I;
typedef double                  D;
typedef float                   F;
typedef bool                    B;
typedef char                    C;
typedef string                  S;
typedef vector <string>         VS;
typedef vector <int>            VI;
typedef vector <char>           VC;

/* Functions */

I GCD (I x, I y){if (x%y==0) return y; else return (GCD(y,x%y));}
I prime[1002002]={0};
void init(void)
{
    I i,j;
    prime[0]=1;
    for (i=4;i<1002002;i+=2)
    {
        prime[i]=1;
    }
    for (i=3;i<=1001;i+=2)
    {
        for (j=i*i;j<1002002;j+=(i+i))
        {
            prime[j]=1;
        }
    }

}

int main()
{
    #ifdef DKRHZ
        freopen("get.txt","r",stdin);
        //freopen("got.txt","w",stdout);
    #endif // DKRHZ
    init();
    bool p,e;
    I x,n,cns;
    while (scanf("%d",&n)==1)
    {
        x=n;
        p=e=false;
        if (!prime[n])
            p=true;
        cns=0;
        while (n>0)
        {
            cns*=10;
            cns+=n%10;
            n/=10;
        }
        if (!prime[cns] && cns!=x)
        {
            e=true;
        }
        if (!p && !e)
        {
            printf("%d is not prime.\n",x);
        }
        else if (p && e)
        {
            printf("%d is emirp.\n",x);
        }
        else if (p && !e)
        {
            printf("%d is prime.\n",x);
        }
    }
    return 0;
}

[DarkknightRHZ]

Hi, can anyone please help me with this code. I have checked everything but still wrong answer!

Code: Select all

#include <bits/stdc++.h>

using namespace std;

#define PB          push_back
#define PF          push_front
#define  V          vector
#define PII         pair <int,int>
#define MII         map <int,int>
#define MSI         map <string,int>
#define MIS         map <int,string>
#define MLI         map <long long int,int>
#define MIL         map <int,long long int>
typedef long long int           LL;
typedef int                     I;
typedef double                  D;
typedef float                   F;
typedef bool                    B;
typedef char                    C;
typedef string                  S;
typedef vector <string>         VS;
typedef vector <int>            VI;
typedef vector <char>           VC;

/* Functions */

I GCD (I x, I y){if (x%y==0) return y; else return (GCD(y,x%y));}
I prime[1002002]={0};
void init(void)
{
    I i,j;
    prime[0]=1;
    for (i=4;i<1002002;i+=2)
    {
        prime[i]=1;
    }
    for (i=3;i<=1001;i+=2)
    {
        for (j=i*i;j<1002002;j+=(i+i))
        {
            prime[j]=1;
        }
    }

}

int main()
{
    #ifdef DKRHZ
        freopen("get.txt","r",stdin);
        //freopen("got.txt","w",stdout);
    #endif // DKRHZ
    init();
    bool p,e;
    I x,n,cns;
    while (scanf("%d",&n)==1)
    {
        x=n;
        p=e=false;
        if (!prime[n])
            p=true;
        cns=0;
        while (n>0)
        {
            cns*=10;
            cns+=n%10;
            n/=10;
        }
        if (!prime[cns] && cns!=x)
        {
            e=true;
        }
        if (!p && !e)
        {
            printf("%d is not prime.\n",x);
        }
        else if (p && e)
        {
            printf("%d is emirp.\n",x);
        }
        else if (p && !e)
        {
            printf("%d is prime.\n",x);
        }
    }
    return 0;
}

[SHUVOJITKAR]

why i get runtime error?

import java.util.Scanner;

public class uv2a10235 {

static int Rev(int n){
int x=n;
int k,j=0;
while(x!=0){
k=x%10;
j=j*10+k;
x/=10;
}
return j;

}
static boolean isPrime(int n){
for(int i=2;i<=Math.sqrt(n);i++){
if(n%i==0){
return false;
}
}
return true;
}
private static Scanner in = new Scanner(System.in);
public static void main(String[] args) {
while(in.hasNext()){
int n = in.nextInt();
int m = Rev(n);
if(isPrime(n)==true){


if(n!=m && n>9 && isPrime(m)==true){

System.out.println(n + " is emirp.");
}else {

System.out.println(n + " is prime.");
}
}
else{

System.out.println(n + " is not prime.");
}


}

}
}