백준 2609 Java 자바

https://www.acmicpc.net/problem/2609

2609번: 최대공약수와 최소공배수

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1. gcd 함수 사용X

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

 
public class Main {
 
	public static void main(String[] args)throws IOException{
			
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine()," ");
		int[] a=new int[2];
		ArrayList<Integer> lst = new ArrayList<Integer>();
		a[0]=Integer.parseInt(st.nextToken());
		a[1]=Integer.parseInt(st.nextToken());
		Arrays.sort(a);
		
		for(int i=1;i<=a[1];i++) {
			if(a[0]%i==0&&a[1]%i==0) {
				lst.add(i);
				a[0]/=i;
				a[1]/=i;
				i=1;
			}
		}
		
		int res=1;
		for(int e: lst)
			res*=e;
		System.out.println(res);
		System.out.println(res*a[0]*a[1]);
	}
	
}

2. gcd 함수 사용O

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.*;


public class Main {
    public static int gcd(int a, int b) {
        if (b == 0) return a;
        else return gcd(b, a % b);
    }

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(br.readLine());
        int a = Integer.parseInt(st.nextToken());
        int b = Integer.parseInt(st.nextToken());

        System.out.println(gcd(a, b));
        System.out.println(gcd(a, b) * a / (gcd(a, b)) * b / (gcd(a, b)));


    }
}