题解 | #合并表记录#

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

// 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 time = in.nextInt();
        in.nextLine();
        TreeMap<Integer, Integer> groups = new TreeMap<>();
        // 注意 hasNext 和 hasNextLine 的区别
        while (time-- > 0) { // 注意 while 处理多个 case
            String[] vs = in.nextLine().split(" ");
            Integer group_v = Integer.parseInt(vs[0]);
            Integer val_v = Integer.parseInt(vs[1]);
            if (groups.containsKey(group_v)) {
                groups.put(group_v, groups.get(group_v) + val_v);
            } else {
                groups.put(group_v, val_v);
            }
        }
        for (Map.Entry<Integer, Integer> entry : groups.entrySet()) {
            System.out.println(entry.getKey() + " " + entry.getValue());
        }
    }
}