A reversible prime in any number system is a prime whose "reverse" in that number system is also a prime. For example in the decimal system 73 is a reversible prime because its reverse 37 is also a prime.

Now given any two positive integers N (<10?5??) and D (1<D≤10), you are supposed to tell if N is a reversible prime with radix D.

Input Specification:

The input file consists of several test cases. Each case occupies a line which contains two integers N and D. The input is finished by a negative N.

Output Specification:

For each test case, print in one line Yes if N is a reversible prime with radix D, or No if not.

Sample Input:

73 10
23 2
23 10
-2

Sample Output:

Yes
Yes
No

 1 import java.io.BufferedReader;
 2 import java.io.IOException;
 3 import java.io.InputStreamReader;
 4 
 5 /**
 6  * @Auther: Xingzheng Wang
 7  * @Date: 2019/2/20 22:41
 8  * @Description: pattest
 9  * @Version: 1.0
10  */
11 public class
 
 PAT1015 {
12 
13     public static void main(String[] args) throws IOException {
14         BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
15         while (true) {
16             String[] in = reader.readLine().split(" ");
17             int num = Integer.parseInt(in[0]);
18             if (num < 0) break;
19             int indax = Integer.parseInt(in[1]);
20             if (isprime(num) && isprime(reve(num,indax))) {
21                 System.out.println("Yes");
22             }else{
23                 System.out.println("No");
24             }
25         }
26     }
27 
28     private static int reve(int num, int indax) {
29         StringBuilder sb = new StringBuilder(Integer.toString(num, indax)).reverse();
30         return Integer.parseInt(sb.toString(), indax);
31     }
32 
33     private static boolean isprime(int num){
34         if(num == 1) return false;
35         for (int i = 2; i <= Math.sqrt(num); i++) {
36             if (num % i == 0)
37                 return false;
38         }
39         return true;
40     }
41 }

[PAT] 1015 Reversible Primes （20 分）Java