题解 | #合并表记录#

import java.util.Map;
import java.util.Scanner;
import java.util.TreeMap;
import java.util.Iterator;

// 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);
        Map<Integer, Integer> map = new TreeMap<>();
        int total = in.nextInt();
        for (int i = 0; i < total; i++) {
            int key = in.nextInt();
            int value = in.nextInt();
            if(map.containsKey(key)) map.put(key,map.get(key)+value);
            else map.put(key,value);
        }
        Iterator iterator=map.keySet().iterator();
        while(iterator.hasNext()){
            int key=(int)iterator.next();
            int value=map.get(key);
            System.out.println(key+" "+value);
        }

    }
}