백준 9613번 - GCD합 (Java 8)

https://www.acmicpc.net/problem/9613

9613번: GCD 합

코드 :

최대공약수, 유클리드 호제법

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

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        StringTokenizer st;
        int t = Integer.parseInt(br.readLine());
        int[] arr;
        while(t-- >0){
            st = new StringTokenizer(br.readLine());
            int n = Integer.parseInt(st.nextToken());
            long sum = 0;

            arr = new int[n];
            for (int i = 0; i < n; i++) {
                arr[i] = Integer.parseInt(st.nextToken());
            }

            for (int i = 0; i < n-1 ; i++) {
                for (int j = i+1; j < n; j++) {
                    sum += GCD(arr[i], arr[j]);
                }
            }
            sb.append(sum).append("\n");
        }
        System.out.print(sb);
    }
    public static int GCD(int num1, int num2){
        int r = num1 % num2;
        if(r ==0){
            return num2;
        }

        return GCD(num2, r);
    }
}