[2022 KAKAO BLIND RECRUITMENT] k진수에서 소수 개수 구하기

https://programmers.co.kr/learn/courses/30/lessons/92335

코딩테스트 연습 - k진수에서 소수 개수 구하기

 

파이썬

def is_prime(num: int) -> bool:
    for i in range(2, int((num + 1) ** 0.5) + 1):
        if num % i == 0:
            return False
    return True


def change_notation(n: int, k: int) -> str:
    new_num = ''
    while n > 0:
        m = n % k
        new_num += str(m)
        n = n // k
    return new_num[::-1]


def solution(n, k):
    new_num = change_notation(n, k)
    new_nums = new_num.split('0')
    answer = 0
    for each in new_nums:
        if each == '':
            continue
        each = int(each)
        if each > 1 and is_prime(each):
            answer += 1
    return answer

 

자바

class Solution {
    boolean is_prime(long n) {
        if (n < 2) return false;
        for (var i = 2; i < (long) Math.sqrt(n + 1) + 1; i++) {
            if (n % i == 0)
                return false;
        }
        return true;
    }

    String change_notation(int n, int k) {
        int m;
        var new_num = new StringBuilder();
        while (n > 0) {
            m = n % k;
            new_num.append(m);
            n = n / k;
        }
        return new_num.reverse().toString();
    }

    public int solution(int n, int k) {
        int answer = 0;
        String[] nums = change_notation(n, k).split("0+");
        for (String num : nums)
            if (is_prime(Long.parseLong(num)))
                answer++;
        return answer;
    }
}