题解 | #合并表记录#

import java.util.Scanner;
import java.util.HashMap;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int a = in.nextInt();
        HashMap<Integer,Integer> map = new HashMap<Integer,Integer>(a);
        for(int i=1; i<=a; i++){
            int index = in.nextInt();
            int value = in.nextInt();
            if(map!=null && map.containsKey(index)){
                map.put(index,map.get(index)+value);
            }else {
                map.put(index,value);
            }
        }
        for(int key : map.keySet()){
            System.out.println(key + " " + map.get(key));
        }
    }
}