HDU 6168 - Numbers | 2017 ZJUT Multi-University Training 9

/*
HDU 6168 - Numbers [ 思维 ]  |  2017 ZJUT Multi-University Training 9
题意:
	....
分析：
	全放入multiset 从小到大,慢慢筛
*/
#include <bits/stdc++.h>
using namespace std;
const int N = 125250;
int n, s[N];
int a[N], cnt;
multiset<int> st;
multiset<int>::iterator it, pos;
int main()
{
    int x;
    while (~scanf("%d", &n))
    {
        st.clear();
        for (int i = 1; i <= n; ++i)
        {
            scanf("%d", &x);
            st.insert(x);
        }
        cnt = 0;
        for (it = st.begin(); it != st.end(); it++)
        {
            a[++cnt] = *it;
            for (int i = 1; i < cnt; i++)
            {
                pos = st.find(a[i]+a[cnt]);
                st.erase(pos);
            }
        }
        printf("%d\n", cnt);
        for (int i = 1; i < cnt; i++) printf("%d ", a[i]);
        if (cnt) printf("%d\n", a[cnt]);
    }
}