PAT 甲级 刷题日记|A 1120 Friend Numbe

思路：

set 内部自动有序且不含重复元素的容器。非常适合本题。

代码

#include <bits/stdc++.h>
using namespace std;

const int maxn = 10003;
int n, all = 0;
int num[maxn];
set<int> ans;

int main() {
    cin>>n;
    for (int i = 0; i < n; i++) {
        cin>>num[i];
        int sum = 0;
        while (num[i] != 0) {
            sum += num[i] % 10;
            num[i] /= 10;
        }
        ans.insert(sum);
    }
    cout<<ans.size()<<endl;
    for (auto it = ans.begin(); it != ans.end(); it++) {
        if (it == ans.begin()) ;
        else cout<<" ";
        cout<<*it;
    }
}