코영방

https://www.acmicpc.net/problem/1929

#include <bits/stdc++.h>
using namespace std;
//소수 구하기
int main() {
	int n, m;
	cin >> n >> m;
	for (int i=n; i<=m; i++) {
		bool prime = true;
		if (i == 1) prime = false;
		else {
			for (int j=2; j*j<=i; j++) {
				if (i % j == 0) {
					prime = false;
					break;
				}
			}
		}
		if (prime) printf("%d\n", i);
	}
}

https://www.acmicpc.net/problem/1978

#include <bits/stdc++.h>
using namespace std;
//소수 찾기
int main() {
	bool prime = true;
	int n, arr[100], cnt = 0;
	cin >> n;
	for (int i=0; i<n; i++) {
		cin >> arr[i];
	}
	for (int i=0; i<n; i++) {
		if (arr[i] == 1) {
			prime = false;
		}
		else {
			for (int j=2; j*j<=arr[i]; j++) {
				if (arr[i] % j == 0) {
					prime = false;
					break;
				}
			}	
		}
		if (prime) cnt++;
		else prime = true;
	}
	printf("%d", cnt);
}

www.jungol.co.kr/bbs/board.php?bo_table=pbank&wr_id=1174&sca=2040

import math
def is_prime_number(x):
  for i in range(2, int(math.sqrt(x))+1):
    if x%i == 0:
      return False
  return True

m = int(input())

for _ in range(0,m):
  i = int(input())
  u = i+1
  d = i-1
  while True:
    flag = False
    p = ""
    if is_prime_number(d):
      flag = True
      p += str(d) + " "
      #print(d)

    if is_prime_number(u):
      flag = True
      p += str(u) + " "
      #print(u)
    

    if flag == True:
      print(p)
      break
    
    u+=1
    d-=1