1. 暴力

import java.util.*;

public class Main{
    static int N = 1010;
    static int[] h = new int[4010];
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int t = sc.nextInt();
        for(int i = 0; i < t; i ++){
            int n = sc.nextInt();
            Arrays.fill(h, 0);
            int k = 0;
            int cnt = 0;
            while(h[k] == 0){
                h[k] = 1;
                k = (k + n + 1) % (4 * n);
                cnt ++;
            }
            System.out.println(cnt + 1);
        }
    }
}

2. gcd

import java.util.*;

public class Main{
    static int N = 1010;
    static int[] h = new int[4010];
    public static int gcd(int a, int b){
        return b == 0? a: gcd(b, a % b);
    }
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int t = sc.nextInt();
        for(int i = 0; i < t; i ++){
            int n = sc.nextInt();
            int d = gcd(4 * n, n + 1);
            System.out.println(4 * n / d + 1);
        }
    }
}