题解 | #合并表记录#

import java.util.Scanner;

import java.util.Map;
import java.util.TreeMap;


// 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);

        int count = in.nextInt();
        int index = 1;
        Map<Integer, Integer> map = new TreeMap<>();
        in.nextLine();
        while (index<=count) {
            index++;
            String pair = in.nextLine();
         
            if(pair.length()==0){
                continue;
            }
            String[] pairArray = pair.split(" ");
            if (null == map.get(Integer.parseInt(pairArray[0]))) {
                map.put(Integer.parseInt(pairArray[0]), Integer.parseInt(pairArray[1]));
            } else {
                map.put(Integer.parseInt(pairArray[0]),
                        map.get(Integer.parseInt(pairArray[0])) + Integer.parseInt(pairArray[1]));
            }
        }
        for(Integer key:map.keySet()){
            System.out.print(key);
            System.out.print(" ");
            System.out.println(map.get(key));
        }
    }
}