2512. Reward Top K Students

You are given two string arrays positive_feedback and negative_feedback, containing the words denoting positive and negative feedback, respectively. Note that no word is both positive and negative.

Initially every student has 0 points. Each positive word in a feedback report increases the points of a student by 3, whereas each negative word decreases the points by 1.

You are given n feedback reports, represented by a 0-indexed string array report and a 0-indexed integer array student_id, where student_id[i] represents the ID of the student who has received the feedback report report[i]. The ID of each student is unique.

Given an integer k, return the top k students after ranking them in non-increasing order by their points. In case more than one student has the same points, the one with the lower ID ranks higher.

class Solution {
    string parse(string& s, int& p) {
        if(s[p] == ' ') p += 1;
        string res = "";
        while(p < s.length() and s[p] != ' ') res.push_back(s[p++]);
        return res;
    }
public:
    vector<int> topStudents(vector<string>& A, vector<string>& B, vector<string>& report, vector<int>& id, int k) {
        unordered_set<string> pos(begin(A), end(A));
        unordered_set<string> neg(begin(B), end(B));
        unordered_map<int,int> mp;
        for(int i = 0; i < id.size(); i++) {
            int now = 0, p = 0;
            while(p < report[i].size()) {
                auto token = parse(report[i], p);
                if(pos.count(token)) now += 3;
                if(neg.count(token)) now -= 1;
            }
            mp[id[i]] += now;
        }
        vector<pair<int,int>> rank;
        for(auto [k,v] : mp) rank.push_back({v,k});
        sort(begin(rank), end(rank), [](auto a, auto b) {
           if(a.first == b.first) return a.second < b.second;
           return a.first > b.first;
        });
        vector<int> res;
        for(int i = 0; i < k; i++) {
            res.push_back(rank[i].second);
        }
        return res;
    }
};