题解 | #合并表记录#

使用TreeMap来存储数据，可以省去排序操作。

public class Main {
    static TreeMap<Integer, Integer> treemap = new TreeMap<>();

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        for (int i = 0; i < n; i ++) {
            int temp = in.nextInt();
            treemap.put(temp, treemap.getOrDefault(temp, 0) + in.nextInt());
        }
        //下面是遍历TreeMap的方式
        Iterator it = treemap.entrySet().iterator();
        while (it.hasNext()) {
            Map.Entry entry = (Map.Entry)it.next();
            int key = (Integer)entry.getKey();
            int value = (Integer)entry.getValue();
            System.out.println(key + " " + value);
        }
        in.close();
    }
}