class Solution {
private:
    int cnt[30];
    vector<vector<int>> res;
    vector<int> path;

    void dfs(int p) {
        if (p > 10) {
            res.push_back(path);
            return;
        }
        for (int i = 0; i < cnt[p + 10] + 1; ++i) {
            dfs(p + 1);
            path.push_back(p);
        }
        for (int i = 0; i < cnt[p + 10] + 1; ++i) {
            path.pop_back();
        }
    }
public:
    vector<vector<int>> subsetsWithDup(vector<int>& nums) {
        for (int i: nums) {
            ++cnt[i + 10];
        }

        dfs(-10);

        return res;
    }
};