GCDFast.java

import java.util.*;
import java.io.*;

public class GCDFast{
    public static void main(String[] args){
        Scanner s = new Scanner(System.in);
        int n1 = s.nextInt();
        int n2 = s.nextInt();
        if (n2 > n1){
            swap(n1, n2);
        }
        System.out.println(getGCD(n1, n2));
    }
    static int[] swap (int n1, int n2){
        int[] arr = new int[2];
        arr[0] = n1 - n2;
        arr[1] = arr[0] + n2;
        arr[0] = arr[1] - arr[0];
        return arr;
    }
    static int getGCD(int n1, int n2){
        if (n1%n2 == 0){
            return n2;
        }
        else {
            while (n2 != 0){
                int temp = n2; //storing divisor
                n2 = n1%n2; //updating remainder which will be used as divisor
                n1 = temp; //updating with divisor which will be used as dividend
            }
            return n1; //returning divisor when n2 i.e., remainder is zero
        }
    }
}