Create 2353. Design a Food Rating System (#366)

2353. Design a Food Rating System

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+struct ComparePairs
+{
+    bool operator()(const pair<int, string> &p1, const pair<int, string> &p2)
+    {
+        if (p1.first != p2.first)
+            return p1.first < p2.first; // food with the highest rating will be at the top
+
+        return p1.second > p2.second; // if rating is same, then food with that comes first in alphabetical order gets higher priority
+    }
+};
+
+class FoodRatings
+{
+public:
+    unordered_map<string, priority_queue<pair<int, string>, vector<pair<int, string>>, ComparePairs>> m;
+    unordered_map<string, int> r;
+    unordered_map<string, string> c;
+
+    FoodRatings(vector<string> &foods, vector<string> &cuisines, vector<int> &ratings)
+    {
+
+        for (int i = 0; i < foods.size(); ++i)
+        {
+            c[foods[i]] = cuisines[i];
+            m[cuisines[i]].push({ratings[i], foods[i]});
+            r[foods[i]] = ratings[i];
+        }
+    }
+
+    void changeRating(string food, int newr)
+    {
+        r[food] = newr;
+        string cs = c[food];
+        m[cs].push({newr, food});
+    }
+
+    string highestRated(string cuisine)
+    {
+        pair<int, string> p;
+        while (1)
+        {
+            p = m[cuisine].top();
+
+            if (r[p.second] != p.first)
+                m[cuisine].pop();
+            else
+                return p.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);
+ */