题解 | #合并表记录#

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

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);  
        int n = scanner.nextInt();  
        Map<Integer, Integer> map = new TreeMap<>();  
        for (int i = 0; i < n; i++) {  
            int index = scanner.nextInt();  
            int value = scanner.nextInt();  
            map.put(index, map.getOrDefault(index, 0) + value);  
        }  
        for (Map.Entry<Integer, Integer> entry : map.entrySet()) {  
            System.out.println(entry.getKey() + " " + entry.getValue());  
        }  
    }
}