数据表记录包含表索引和数值，请对表索引相同的记录进行合并，即将相同索引的数值进行求和运算，输出按照key值升序进行输出。

import java.util.Scanner;

import java.util.SortedMap;

import java.util.TreeMap;

public class Main {

    public static void main(String[] args) {

        Scanner str = new Scanner(System.in);

        SortedMap<Integer,Integer> map = new TreeMap<>();

        int n = Integer.parseInt(str.nextLine());

        for (int i = 0;i<n;i++){

            String[] mid = str.nextLine().split("\\s+");

            addPare(map,mid);

        }

        System.out.println(mapToString(map));

    }

    private static String mapToString(SortedMap<Integer, Integer> map) {

        // TODO Auto-generated method stub

        StringBuilder builder = new StringBuilder();

        for(SortedMap.Entry<Integer,Integer>e:map.entrySet()){

            builder.append(e.getKey()).append(" ").append(e.getValue()).append("\r");

        }

        return builder.toString();

    }

    private static void addPare(SortedMap<Integer, Integer> map, String[] mid) {

        // TODO Auto-generated method stub

        int key = Integer.parseInt(mid[0]);

        int value = Integer.parseInt(mid[1]);

        if(map.containsKey(key)){

            map.put(key, map.get(key) + value);

        }else{

            map.put(key, value);

        }

    }

}