题解 | #合并表记录#

import java.io.BufferedInputStream;
import java.util.Map;
import java.util.Scanner;
import java.util.TreeMap;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(new BufferedInputStream(System.in));
        Map<Integer, Integer> map = new TreeMap<>();
        while (sc.hasNext()) {
            int rows = Integer.parseInt(sc.nextLine());
            for (int i = 0; i < rows; i++) {
                String[] lines = sc.nextLine().split(" ");
                int key = Integer.parseInt(lines[0]);
                int value = Integer.parseInt(lines[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));
        }
    }
}