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);
        HashMap<Integer, Integer> stringStringHashMap = new HashMap<>();
        int count = scanner.nextInt();
        for (int i = 0; i < count; i++) {
            Integer s1 = scanner.nextInt();
            Integer s2 = scanner.nextInt();
            //String[] s1 = s.split(" ");
            if (stringStringHashMap.containsKey(s1)) {
                Integer v = stringStringHashMap.get(s1);
                v = v + s2;
                stringStringHashMap.put(s1, v);
            } else {
                stringStringHashMap.put(s1, s2);
            }
        }
        Set<Integer> integers = stringStringHashMap.keySet();
        List<Integer> strings = new ArrayList<>();
        for (Integer integer : integers) {
            strings.add(integer);
        }
        Collections.sort(strings);
        for (Integer integer : strings) {
            System.out.println(integer + " " + stringStringHashMap.get(integer));
        }
    }
}