2n个数字进行匹配相邻不重复

n = 5时：

import java.util.Arrays;
import java.util.Scanner;

public class Main {
    static final int N = 2010;
    static int[] a = new int[N];
    static int n;

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int T = sc.nextInt();
        while (T-- > 0) {
            n = sc.nextInt();
            for (int i = 1; i <= 2 * n; i++) {
                a[i] = sc.nextInt();
            }

            Arrays.sort(a, 1, 2 * n + 1);
            int max_cnt = 0;
            for (int i = 1; i <= 2 * n; i++) {
                int j = i, cnt = 0;
                while (j <= 2 * n && a[j] == a[i]) {
                    cnt ++;
                    j++;
                }
                max_cnt = Math.max(max_cnt, cnt);
                i = j - 1;
            }

            int zero_cnt = max_cnt - n;
            if (zero_cnt <= n - zero_cnt + 1) {
                System.out.println("YES");
            } else {
                System.out.println("NO");
            }
        }
    }
}