PAT_B_1064_Java(20分)

import java.io.*;
import java.util.Set;
import java.util.TreeSet;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
        int n = Integer.parseInt(bf.readLine());
        String[] str = bf.readLine().split(" ");
        //第一次使用TreeSet，相比于HashSet的无序性，能够对存入的数据排好序
        Set<Integer> set = new TreeSet<Integer>();
        //将所有朋友数存入set中，set会排除掉重复数值
        for (int i = 0; i < str.length; i++) {
            if (set.contains(adad(str[i]))) {
                continue;
            } else {
                set.add(adad(str[i]));
            }
        }
        //输出朋友数个数
        System.out.println(set.size());
        //遍历set集合，由于已经排好序，从头到尾遍历输出即可
        boolean isFirst = true;
        for (int id : set) {
            if (!isFirst) {
                System.out.print(" ");
            }
            System.out.print(id);
            isFirst = false;
        }
    }

    //返回三位加和
    public static int adad(String str) {
        int n = Integer.parseInt(str);
        int sum = 0;
        /*
        int ge = n % 10;
        int shi = n % 100 / 10;
        int bai = n / 100;
        */
        while(n!=0){
            sum+=n%10;
            n/=10;
        }
        return sum;
    }
}