1120 Friend Numbers（20 分）

#include<iostream>
#include<vector>
#include<string>
#include<algorithm>
#include<set>

using namespace std;

int main()
{
    int M;
    int sum;
    string str;
    set<int> s;
    cin >> M;
    for (int i = 0; i < M; i++)
    {
        sum = 0;
        cin >> str;
        for (auto c : str)
            sum += atoi(&c); //可以更换为 sum += c - '0';

        s.insert(sum);
    }

    cout << s.size() << endl;
    auto it = s.begin();
    cout << *it;
    for (it++; it !=s.end();it++ )
    {
        cout << " " << *it;
    }
    system("pause");
    return 0;
}