题解 | #合并表记录#

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);
        HashMap<Integer, Integer> map = new HashMap<>();
        int m=in.nextInt();
        while (m!=0) { // 注意 while 处理多个 case
            int a = in.nextInt();
            int b = in.nextInt();
            if (map.containsKey(a)) {
                map.replace(a, b + map.get(a));
            }else{
                map.put(a,b);
            }
            m--;
        }
        TreeMap<Integer, Integer> sortedMap = new TreeMap<>(map);
        for (Map.Entry<Integer, Integer> entry : sortedMap.entrySet()) {
          System.out.println(entry.getKey() + " " + entry.getValue());
      }
      in.close();
    }
}