北京理工考研机试 三元组 模拟 TreeMap 细节满满

算法题解专栏

---

分组统计

输出

1
7
3 2 3 8 8 2 3
1 2 3 2 1 3 1

输出

1={2=0,3=2,8=1}
2={2=1,3=0,8=1}
3={2=1,3=1,8=0}

---

模拟
多次使用的数组记得初始化
TreeMap：有序集合按键进行排序
二维数组也行

import java.util.*;

public class Main
{
	static int[] m = new int[1010];// 记录什么数出现过

	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		int T = sc.nextInt();
		while (T-- > 0)
		{
			int n = sc.nextInt();
			int[] a = new int[n];
			int[] c = new int[n];// 记录 i 所在的小组编号
			Arrays.fill(m, 0);
			for (int i = 0; i < n; i++)
			{
				a[i] = sc.nextInt();
				m[a[i]] = 1;
			}
			ArrayList<Integer> list = new ArrayList<>();
			for (int i = 0; i <= 1000; i++)
				if (m[i] == 1)
					list.add(i);

//			HashSet set = new HashSet<>();
			int num = -1;
			for (int i = 0; i < n; i++)
			{
				c[i] = sc.nextInt();
				num = Math.max(c[i], num);
			}

			int[] cnt = new int[1010];// 计数数组，记录 i 出现的次数

			for (int i = 1; i <= num; i++)// 枚举每一组
			{
				Arrays.fill(cnt, 0);
				System.out.print(i + "={");
				for (int j = 0; j < n; j++)// 枚举所有数对应的组
				{
					if (c[j] == i)
					{
						cnt[a[j]]++;
					}
				}
				int size = list.size();
				for (int j = 0; j < size - 1; j++)
				{

					System.out.print(list.get(j) + "=" + cnt[list.get(j)] + ",");
				}
				System.out.print(list.get(size - 1) + "=" + cnt[list.get(size - 1)]);

				System.out.println("}");
			}
		}
	}
}