题解 | #合并表记录#

import java.util.*;

// 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) {
        combine();
    }

        /**
     * HJ8 合并表记录
     */
    private static void combine() {
        Scanner in = new Scanner(System.in);
        int num = in.nextInt();
        Map<Integer, Integer> map = new TreeMap<>();
        while (num > 0) {
            int key = in.nextInt();
            int value = in.nextInt();
            map.compute(key, (k, v) -> v == null ? value : v + value);
            num--;
        }
        map.forEach((key, value) -> System.out.println(key + " " + value));
    }

}