藏书问题~

package com.example.mybatisplus.MyCloneable;
import java.util.*;
public class demo1 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        List<String> stringList = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            stringList.add(scanner.next());
        }
        // 使用 Map 来统计每种图书的个数
        Map<String, Integer> bookCountMap = new HashMap<>();
        for (String book : stringList) {
            if (bookCountMap.containsKey(book)) {
                // 如果图书已经在 map 中存在，增加其计数
                int count = bookCountMap.get(book);
                bookCountMap.put(book, count + 1);
            } else {
                // 如果图书不在 map 中，添加并设置计数为 1
                bookCountMap.put(book, 1);
            }
        }
        //输出Map中键的个数
        Set<String> keys = bookCountMap.keySet();
        System.out.println(keys.size());
        // 遍历 Map 并输出图书的种类和个数
        for (Map.Entry<String, Integer> entry : bookCountMap.entrySet()) {
            String book = entry.getKey();
            int count = entry.getValue();
            System.out.println(book + " " + count);
        }
    }
}