浙江理工大学每日一题3.14

#pragma GCC optimize(1)
#pragma GCC optimize(2)
#pragma GCC optimize(3, "Ofast", "inline")
#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
const int N = 1100;
unordered_set<int> q;
int sum[N], ans[N], s[N], n;
bool flag;
void dfs(int i, int l, int r, int suml, int sumr)
{
    if (l > r)//此时说明数组已经填完
    {
        int a = 0;
        for (int i = 1; i <= n; i++)
            a += ans[i];
        if (a != sum[n * 2])
            return;
        flag = true;
    }
    if (flag)
        return;
    int qian = sum[i] - suml;//假设第i个是前缀
    int hou = sum[i] - sumr;
    if (q.find(qian) == q.end() && q.find(hou) == q.end())
        return;
    if (q.find(qian) != q.end())
    {
        ans[l] = qian;
        dfs(i + 1, l + 1, r, suml + qian, sumr);
    }
    if (flag)
        return;
    if (q.find(hou) != q.end())
    {
        ans[r] = hou;
        dfs(i + 1, l, r - 1, suml, sumr + hou);
    }
}
int main()
{
    int m;
    cin >> n;
    for (int i = 1; i <= n * 2; i++)
        cin >> sum[i];
    sort(sum + 1, sum + n * 2 + 1);
    cin >> m;
    while (m--)
    {
        int x;
        cin >> x;
        q.insert(x);
    }
    dfs(1, 1, n, 0, 0);
    for (int i = 1; i <= n; i++)
        cout << ans[i] << " ";
    system("pause");
    return 0;
}