Leetcode 1176 Solution

class Leaderboard {
    std::multiset<std::pair<int, int>> s;
    std::unordered_map<int, int> scores;

public:
    Leaderboard() {
    }

    void addScore(int playerId, int score) {
        if (scores.find(playerId) != scores.end())
        {
            s.erase(std::make_pair(scores[playerId], playerId));

            int new_score = score + scores[playerId];
            scores[playerId] = new_score;
            s.insert(std::make_pair(new_score, playerId));
        }
        else
        {
            scores[playerId] = score;
            s.insert(std::make_pair(score, playerId));
        }
    }

    int top(int K) {
        int sum = 0;
        int i = 0;
        for (auto it = s.rbegin(); it != s.rend() && i < K; it++, i++)
            sum += it->first;
        return sum;
    }

    void reset(int playerId) {
        s.erase(std::make_pair(scores[playerId], playerId));
        scores.erase(playerId);
    }
};

/**
 * Your Leaderboard object will be instantiated and called as such:
 * Leaderboard* obj = new Leaderboard();
 * obj->addScore(playerId,score);
 * int param_2 = obj->top(K);
 * obj->reset(playerId);
 */