HackerRank String Query

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

vector<int> compute(vector<string> &words, map<string, vector<int>> &Map) {
    vector<int> Set1(Map[words[0]].begin(), Map[words[0]].end());
    for(int i = 1; i < words.size(); i++) {
        vector<int> Set2(Map[words[i]].begin(), Map[words[i]].end());
        vector<int> Set3(Set1.size());
        vector<int> Set4(Set1.size());
        auto it = set_difference(Set1.begin(), Set1.end(), Set2.begin(), Set2.end(), Set3.begin());
        it = set_difference(Set1.begin(), Set1.end(), Set3.begin(), it, Set4.begin());
        Set1.clear();
        for(auto iter = Set4.begin(); iter != it; iter++) {
            Set1.push_back(*iter);
        }
    }
    if(Set1.size() == 0) {
        Set1.push_back(-1);
    }
    return Set1;
}

int main() {
	// your code goes here
	int n;
	cin >> n;
	string sentence[n];
	map<string, vector<int>> Map;
	getline(cin, sentence[0]);
	for(int i = 0; i < n; i++) {
	    getline(cin, sentence[i]);
	}
	for(int i = 0; i < n; i++) {
	    sentence[i] += " ";
	    string word = "";
	    for(int j = 0; j < sentence[i].length(); j++) {
	        if(sentence[i][j] != ' ') 
	        word += sentence[i][j];
	        else {
	            Map[word].push_back(i);
	            word = "";
	        }
	    }
	}
	int q;
	cin >> q;
	vector<vector<int>> ans(q, vector<int>());
	string queries[q];
	getline(cin, queries[0]);
	for(int i = 0; i < q; i++) {
	    getline(cin, queries[i]);
	}
	for(int i = 0; i < q; i++) {
	    queries[i] += " ";
	    string word = "";
	    vector<string> words;
	    for(int j = 0; j < queries[i].length(); j++) {
	        if(queries[i][j] != ' ') 
	        word += queries[i][j];
	        else {
	            words.push_back(word);
	            word = "";
	        }
	    }
	    vector<int> temp = compute(words, Map);
	    for(int j = 0; j < temp.size(); j++) {
	         ans[i].push_back(temp[j]);
	    }
	}
	for(int i = 0; i < ans.size(); i++) {
	    for(int j = 0; j < ans[i].size(); j++) {
	        cout << ans[i][j] << " ";
	    }
	    cout << endl;
	}
	return 0;
}