这题目什么意思。。。
1015. Reversible Primes (20)
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
AC代码
#include<iostream>#include<cstdio>#include<memory.h>#include<algorithm>#include<cstring>#include<queue>#include<cmath>#include<vector>#include<cstdlib>#include<cmath>#include<iomanip>#include<string>using namespace std;#define MAX 0x6fffffffbool isprime(int n){ if(n==1) return false; int q = sqrt(n+0.0); for(int i=2;i<=q;++i){ if(n%i==0) return false; } return true;}int reverse(int n, int radix){ int ans = 0; while(n>0){ ans = ans*radix + n%radix; n /= radix; } return ans;}int main(){ //freopen("in.txt", "r", stdin); int n, d; while(cin>>n, n>=0){ cin>>d; if(isprime(n) && isprime(reverse(n, d))) printf("Yes\n"); else printf("No\n"); } // fclose(stdin); return 0;}