PATA1120_STL（set）

set只能通过迭代器访问，只有vector和string可以通过*（it+i）来访问

#include<bits/stdc++.h>
using namespace std;
set<int> st;
int main() {
    int n, a;
    scanf ("%d", &n);
    for (int i = 0; i < n; i++) {
        scanf ("%d", &a);
        int sum = 0;
        while (a != 0) {
            int now = a % 10;
            a = a / 10;
            sum += now;
        }
        st.insert(sum);
    }
    cout << st.size() << endl;
    for (auto it = st.begin(); it != st.end(); it++) {
        if (it != st.begin()) printf (" ");
        cout << *it;
    }
    return 0;
}