题解 | #合并表记录#

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Map<Integer, Integer> map = new TreeMap<Integer, Integer>();
        while (sc.hasNext()) {
            int a = sc.nextInt();
            int b = sc.nextInt();
            if (map.containsKey(a)) {
                map.put(a, b + map.get(a));
            } else {
                map.put(a, b);
            }
        }
        map.forEach((key, value) -> System.out.println(key + " " + value));
    }
}

思路：treeMap实现自然顺序排序