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);
        while (in.hasNextLine()) {
            String num = in.nextLine();
            TreeMap<Integer, Integer> m = new TreeMap<>();
            for (int i = 0; i < Integer.valueOf(num); i++) {
                String str = in.nextLine();
                String[] arr = str.split(" ");
                if (null == m.get(Integer.valueOf(arr[0]))) {
                    m.put(Integer.valueOf(arr[0]), Integer.valueOf(arr[1]));
                } else {
                    m.put(Integer.valueOf(arr[0]),
                          Integer.valueOf(arr[1]) + m.get(Integer.valueOf(arr[0])));
                }
            }
            for (Map.Entry<Integer, Integer> e : m.entrySet()) {
                System.out.println(e.getKey() + " " + e.getValue());
            }
        }
    }
}