题解 | #合并表记录#

import java.util.Hashtable;
import java.util.Iterator;
import java.util.Scanner;
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 = 0;
        if(in.hasNextLine()){
            count = Integer.parseInt(in.nextLine());
        }
        TreeMap<Integer,Integer> tree = new TreeMap();
        int index;
        int value;
        String st = "";
        while(count>0){
            st = in.nextLine();
            //System.out.println(st.split(" ")[0]);
            index = Integer.parseInt(st.split(" ")[0]);
            value = Integer.parseInt(st.split(" ")[1]);
            if(tree.containsKey(index)){
                tree.put(index,tree.get(index)+value);
            }else{
                tree.put(index,value);
            }
            count--;
        }
        Iterator<Integer> iterator = tree.keySet().iterator();
        while(iterator.hasNext()){
            Integer key = iterator.next();
            System.out.println(key+" "+ tree.get(key));
        }
        in.close();
    }
}