PAT--1015. Reversible Primes

题解

#include <iostream>
#include <cstdio>
#include <string>
#include <cmath>
#include <algorithm>
using namespace std;

bool isPrime(int n){

if(n < 2) return false;

int k = sqrt(n);
for(int i = 2; i <= k; ++i){
if(n % i == 0) return false;
}
return true;
}

bool solve(int N, int D){

if(!isPrime(N)) return false;

string n;
while(N){
n += N % D + '0';
N /= D;
}
int res = 0;
for(int i = 0; i < n.length(); ++i){
res = res * D + (n[i] - '0');
}

return isPrime(res);
}

int main(){

int N, D;
while(cin >> N && N >= 0){
cin >> D;
cout << (solve(N, D) ? "Yes" : "No") << endl;
}

return 0;
}