백준 2839

코딩테스트 조지러 함 가보자 ~

import java.io.*;

public class Main {
	public static void main(String[] args) throws IOException {
    	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int N = Integer.parseInt(br.readLine());
        int count = 0;
        
        while (true) {
        	if (N % 5 ==0) {
            	count += (N / 5);
                break;
            } else {
            	N -= 3;
                count++;
            }
            
            if (N < 0) {
            	count = -1;
                break;
            }
        }
        
        System.out.println(count);
    }
}

import java.io.*;

public class Main {
	public static void main(String[] args) throws IOException {
    	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        int count = 0;
		
        while (n > 2) {
        	if (n % 5 != 0) {
            	n -= 3;
                count++;
                
                if (n % 5 %% n % 3 != 0) { //  5와 3으로 나누어 떨어지지 않으면
                	count = -1;
                    n = count;
                }
                
            } else {
            	count += n / 5;
                break;
            }
        }
        System.out.println(count);
    }
}

참조

https://www.acmicpc.net/problem/2839