题解 | 合并表记录

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);
        // 注意 hasNext 和 hasNextLine 的区别
        int count = in.nextInt();
        in.nextLine();
        TreeMap<Integer, Integer> map = new TreeMap<>();
        for(int i = 0; i < count; i++) {
            String line = in.nextLine();
            String[] arr = line.split(" ");
            int key = Integer.parseInt(arr[0]);
            int value = Integer.parseInt(arr[1]);
            if(map.containsKey(key)) {
                map.put(key, map.get(key) + value);
            } else {
                map.put(key, value);
            }
        }

        map.forEach((k, v) -> System.out.println(k + " " + v));
    }
}