PAt A1015 Reversible Primes

1015 Reversible Primes

分数 20

作者 CHEN, Yue

单位 浙江大学

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

 
 给出一个数n，和一个进制数d，将n转换为d进制数，然后将其反转，将反转后的串转换为d进制，令其为m，判断n和m是否都为素数，若是，输出Yes，否则输出No；
 

 

/*** 给出一个数n，和一个进制数d，将n转换为d进制数，然后将其反转，将反转后的串转换为d进制，* 令其为m，判断n和m是否都为素数，若是，输出Yes，否则输出No；
*/#include <iostream>
#include <algorithm>
#include <vector>using namespace std;bool isprime(int n)
{if(n <= 1)  return false;for(int i=2; i<=n/i; ++i)if(n % i == 0)return false;return true;
}vector<int> tostr(int n, int d)
{vector<int> vec;while(n){int mod = n % d;n /= d;vec.push_back(mod);}return vec;
}int stoi(vector<int> vec, int d)
{int v = 0;for(auto ele : vec){v = v * d + ele;}return v;
}int main()
{int n, d;while(cin >> n, n >= 0){cin >> d;vector<int> vec = tostr(n, d);int m = stoi(vec, d);if(isprime(n) && isprime(m))puts("Yes");elseputs("No");}return 0;
}