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 scanner = new Scanner(System.in);
        TreeMap<Integer, Integer> treeMap = new TreeMap<>();


        int count = scanner.nextInt();

        for (int i = 0; i < count; i++) {

            int index = scanner.nextInt();
            int value = scanner.nextInt();

            if (treeMap.containsKey(index)) {
                value = treeMap.remove(index) + value;
                treeMap.put(index, value);

            } else {
                treeMap.put(index, value);

            }


        }

        Set<Integer> integers = treeMap.keySet();
//        TreeSet<Integer> set = new TreeSet<>(new Comparator<Integer>() {
//            @Override
//            public int compare(Integer o1, Integer o2) {
//                return o1.compareTo(o2);
//            }
//        });
        for (Integer integer : integers) {
            System.out.println(integer + " " + treeMap.get(integer));
        }



    }
}