2353. Design a Food Rating System

Design a food rating system that can do the following:

• Modify the rating of a food item listed in the system.
• Return the highest-rated food item for a type of cuisine in the system.

Implement the FoodRatings class:

• FoodRatings(String[] foods, String[] cuisines, int[] ratings) Initializes the system. The food items are described by foods, cuisines and ratings, all of which have a length of n.

• foods[i] is the name of the ith food,
• cuisines[i] is the type of cuisine of the ith food, and
• ratings[i] is the initial rating of the ith food.

• void changeRating(String food, int newRating) Changes the rating of the food item with the name food.
• String highestRated(String cuisine) Returns the name of the food item that has the highest rating for the given type of cuisine. If there is a tie, return the item with the lexicographically smaller name.

Note that a string x is lexicographically smaller than string y if x comes before y in dictionary order, that is, either x is a prefix of y, or if i is the first position such that x[i] != y[i], then x[i] comes before y[i] in alphabetic order.

class Compare {
public:
    bool operator() (pair<int, string> a, pair<int, string> b) {
        if(a.first == b.first) return a.second > b.second;
        return a.first < b.first;
    }
};

class FoodRatings {
    unordered_map<string, string> cmp;
    unordered_map<string, int> rmp;
    unordered_map<string, priority_queue<pair<int, string>, vector<pair<int, string>>, Compare>> rate;
public:
    FoodRatings(vector<string>& foods, vector<string>& cuisines, vector<int>& ratings) {
        int n = foods.size();
        for(int i = 0; i < n; i++) {
            cmp[foods[i]] = cuisines[i];
            rmp[foods[i]] = ratings[i];
            rate[cuisines[i]].push({ratings[i], foods[i]});
        }
    }

    void changeRating(string food, int newRating) {
        rmp[food] = newRating;
        rate[cmp[food]].push({newRating, food});
    }

    string highestRated(string cuisine) {
        auto& heap = rate[cuisine];
        while(rmp[heap.top().second] != heap.top().first) {
            heap.pop();
        }
        return heap.top().second;
    }
};

/**
 * Your FoodRatings object will be instantiated and called as such:
 * FoodRatings* obj = new FoodRatings(foods, cuisines, ratings);
 * obj->changeRating(food,newRating);
 * string param_2 = obj->highestRated(cuisine);
 */