题解 | 合并表记录

import java.util.Scanner;

import java.util.*;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        int row = in.nextInt();
        Map<Integer, Integer> map = new TreeMap<>();
        while (in.hasNextInt()) {
            int key = in.nextInt();
            int value = in.nextInt();
            if (map.containsKey(key)) {
                map.put(key, map.get(key) + value);
            } else {
                map.put(key, value);
            }
        }
        for(Map.Entry<Integer, Integer> e:map.entrySet()) {
            System.out.println(e.getKey() + " " + e.getValue());
        }
    }
}