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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 (< 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 -2Sample Output:
Yes Yes No
1 #include <cstdio> 2 #include <cstring> 3 #include <string> 4 #include <queue> 5 #include <stack> 6 #include <iostream> 7 using namespace std; 8 bool prime[100005]; 9 void getprime(int n){ 10 memset(prime,false,sizeof(prime)); 11 int i,j; 12 prime[2]=true; 13 for(i=3;i<=n;i+=2){ 14 prime[i]=true; 15 for(j=3;j*j<=i;j++){ 16 if(i%j==0){ 17 prime[i]=false; 18 break; 19 } 20 } 21 } 22 } 23 int main(){ 24 //freopen("D:\\INPUT.txt","r",stdin); 25 getprime(100005); 26 int n,d; 27 while(scanf("%d",&n)!=EOF){ 28 if(n<0){ 29 break; 30 } 31 scanf("%d",&d); 32 if(!prime[n]){ 33 printf("No\n"); 34 continue; 35 } 36 queue<int> q; 37 while(n){ 38 q.push(n%d); 39 n/=d; 40 } 41 //cout<<n<<endl; 42 while(!q.empty()){ 43 n*=d; 44 n+=q.front(); 45 q.pop(); 46 } 47 //cout<<n<<endl; 48 if(prime[n]){ 49 printf("Yes\n"); 50 } 51 else{ 52 printf("No\n"); 53 } 54 } 55 return 0; 56 }
pat1015. Reversible Primes (20)
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原文地址：http://www.cnblogs.com/Deribs4/p/4708267.html
