TLE solution

class Solution {

    void make_graph(vector<vector<int>> &graph, int v, vector<bool> &vis){
        vis[v] = 1;
        for(int i = 0; i < 21; ++i){
            if((v >> i) & 1){
                int child = v ^ (1 << i);
                graph[v].push_back(child);
                if(vis[child] == 0){
                    make_graph(graph, child, vis);
                }
            }
        }
    }

    void dfs(vector<vector<int>> &graph, vector<int> &pos, int val, int v){
        if(pos[v] <= val)
            return;
        pos[v] = val;
        for(int &child: graph[v]){
            if(pos[child] <= val)
                continue;
            dfs(graph, pos, val, child);
        }
    }

  public:
    vector<int> solve(int n, vector<string> &s, int Q, vector<string> &q){
        vector<int> ans;
        for(int i = 0; i < n; ++i){
            sort(s[i].begin(), s[i].end());
            auto it = unique(s[i].begin(), s[i].end());
            s[i].resize(it - s[i].begin());
        }
        for(int i = 0; i < Q; ++i){
            sort(q[i].begin(), q[i].end());
        }
        int N = (1 << 22) - 1;
        vector<vector<int>> graph(N + 1);
        vector<bool> vis(N + 1, 0);
        make_graph(graph, N, vis);
        vector<int> pos(N + 1, n + 1);
        for(int i = 0; i < n; ++i){
            int num = 0;
            for(int j = 0; j < s[i].size(); ++j){
                num += (1 << (s[i][j] - 'a'));
            }
            dfs(graph, pos, i, num);
        }
        for(int i = 0; i < Q; ++i){
            int num = 0;
            for(int j = 0; j < q[i].size(); ++j){
                num += (1 << (q[i][j] - 'a'));
            }
            if(pos[num] == n + 1)
                ans.push_back(-1);
            else
                ans.push_back(pos[num]);
        }
        return ans;
    }
};