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);

        int size = in.nextInt();
        HashMap<Integer, Integer> map = new HashMap<>(size);
        while (in.hasNextLine() && in.hasNextInt()) {
            int key = in.nextInt();
            int value = in.nextInt();

            if (map.containsKey(key)) {
                int oldValue = map.get(key);
                map.put(key, oldValue + value);
            } else {
                map.put(key, value);
            }
        }

       for (Integer key : map.keySet()) {
          System.out.println( key + " " + map.get(key));
      }

    }
}