1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
class Solution {

    public boolean isPrime(long n) {
        if(n == 1)  return false;
        long a = (long)Math.sqrt(n) + 1;
        for(int i=2;i<a;i++) {
            if(n%i == 0) return false;
        }
        return true;
    }

    public String[] makeBinList(int n, int k) {
         StringBuilder kBin = new StringBuilder();
         while(n != 0) {
               kBin.insert(0, n%k);
               n /= k;
           }    //k진수 생성
           String[] binList = kBin.toString().split("0");
           // 0을 기준으로 나눔
           return binList;
    }

    public int solution(int n, int k) {
        int answer = 0;

        String[] a = makeBinList(n, k);

       for(String b : a) {
          if(b.equals(""))  continue;

          long c = Long.parseLong(b);
          if(isPrime(c))    answer++;
           }

        return answer;
    }

}