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[PAT] 1015 Reversible Primes (20 分)Java

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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<D10), 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