题解

C++ 见上面，Java 见下面：

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
import java.util.TreeMap;
import java.util.TreeSet;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        HashMap<String, Integer> m1 = new HashMap<>();
        
        // 统计每个字符串出现的次数
        for (int i = 0; i < n; i++) {
            String s = sc.next();
            m1.put(s, m1.getOrDefault(s, 0) + 1);
        }
        
        TreeMap<Integer, TreeSet<String>> m2 = new TreeMap<>();
        
        // 将字符串按照出现次数分组
        for (Map.Entry<String, Integer> entry : m1.entrySet()) {
            int key = -entry.getValue(); // 取负值作为键
            TreeSet<String> set = m2.computeIfAbsent(key, k -> new TreeSet<>()); // 若不存在则创建
            set.add(entry.getKey()); // 添加字符串到 TreeSet
        }
        
        // 输出结果
        for (Map.Entry<Integer, TreeSet<String>> entry : m2.entrySet()) {
            int count = -entry.getKey(); // 计数取负值
            for (String s : entry.getValue()) {
                System.out.println(s + " " + count);
            }
        }
    }
}