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 (< 105) 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
#include<cstdio>bool isPrime(int x){ bool flag=true; if(x==1){ flag=false; } for(int i=2;i*i<=x;i++){ if(x%i==0){ flag=false; break; } } return flag;}int num[110];int main(){ int n,d; while(scanf("%d",&n)!=EOF){ if(n<0) break; scanf("%d",&d); if(isPrime(n)==false){ printf("No/n"); }else{ int len=0; do{ num[len++]=n%d; n/=d; }while(n); int rev=0; for(int i=0;i<len;i++){ rev=rev*d+num[i]; } if(isPrime(rev)==true){ printf("Yes/n"); }else{ printf("No/n"); } } } return 0;}新聞熱點
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