g2301_2400.s2353_design_a_food_rating_system.FoodRatings Maven / Gradle / Ivy

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package g2301_2400.s2353_design_a_food_rating_system;

// #Medium #Hash_Table #Design #Heap_Priority_Queue #Ordered_Set
// #2022_08_07_Time_364_ms_(83.35%)_Space_174.6_MB_(23.97%)

import java.util.Comparator;
import java.util.HashMap;
import java.util.TreeSet;

/**
 * 2353 - Design a Food Rating System\.
 *
 * Medium
 *
 * 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 i^th food,
 *     *   `cuisines[i]` is the type of cuisine of the i^th food, and
 *     *   `ratings[i]` is the initial rating of the i^th 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.
 *
 * **Example 1:**
 *
 * **Input**
 *
 * ["FoodRatings", "highestRated", "highestRated", "changeRating", "highestRated", "changeRating", "highestRated"]
 *
 * [[["kimchi", "miso", "sushi", "moussaka", "ramen", "bulgogi"], ["korean", "japanese", "japanese", "greek", "japanese", "korean"], [9, 12, 8, 15, 14, 7]], ["korean"], ["japanese"], ["sushi", 16], ["japanese"], ["ramen", 16], ["japanese"]]
 *
 * **Output:**
 *
 * [null, "kimchi", "ramen", null, "sushi", null, "ramen"]
 *
 * **Explanation:**
 *
 *     FoodRatings foodRatings = new FoodRatings(["kimchi", "miso", "sushi", "moussaka", "ramen", "bulgogi"], ["korean", "japanese", "japanese", "greek", "japanese", "korean"], [9, 12, 8, 15, 14, 7]);
 *     foodRatings.highestRated("korean"); // return "kimchi"
 *                                         // "kimchi" is the highest rated korean food with a rating of 9.
 *     foodRatings.highestRated("japanese"); // return "ramen"
 *                                           // "ramen" is the highest rated japanese food with a rating of 14.
 *     foodRatings.changeRating("sushi", 16); // "sushi" now has a rating of 16.
 *     foodRatings.highestRated("japanese"); // return "sushi"
 *                                           // "sushi" is the highest rated japanese food with a rating of 16.
 *     foodRatings.changeRating("ramen", 16); // "ramen" now has a rating of 16.
 *     foodRatings.highestRated("japanese"); // return "ramen"
 *                                           // Both "sushi" and "ramen" have a rating of 16.
 *                                           // However, "ramen" is lexicographically smaller than "sushi". 
 *
 * **Constraints:**
 *
 * *   1 <= n <= 2 * 10⁴
 * *   `n == foods.length == cuisines.length == ratings.length`
 * *   `1 <= foods[i].length, cuisines[i].length <= 10`
 * *   `foods[i]`, `cuisines[i]` consist of lowercase English letters.
 * *   1 <= ratings[i] <= 10⁸
 * *   All the strings in `foods` are **distinct**.
 * *   `food` will be the name of a food item in the system across all calls to `changeRating`.
 * *   `cuisine` will be a type of cuisine of **at least one** food item in the system across all calls to `highestRated`.
 * *   At most 2 * 10⁴ calls **in total** will be made to `changeRating` and `highestRated`.
**/
public class FoodRatings {
    private HashMap> cus = new HashMap<>();
    private HashMap foodHashMap = new HashMap<>();

    public FoodRatings(String[] foods, String[] cuisines, int[] ratings) {
        for (int i = 0; i < foods.length; i++) {
            Food food = new Food(foods[i], ratings[i], cuisines[i]);
            foodHashMap.put(foods[i], food);
            if (cus.containsKey(cuisines[i])) {
                cus.get(cuisines[i]).add(food);
            } else {
                TreeSet pq = new TreeSet<>(new Comp());
                pq.add(food);
                cus.put(cuisines[i], pq);
            }
        }
    }

    public void changeRating(String food, int newRating) {
        Food dish = foodHashMap.get(food);
        TreeSet pq = cus.get(dish.cus);
        pq.remove(dish);
        dish.rating = newRating;
        pq.add(dish);
    }

    public String highestRated(String cuisine) {
        return cus.get(cuisine).first().foodItem;
    }

    private static class Comp implements Comparator {
        public int compare(Food f1, Food f2) {
            if (f1.rating == f2.rating) {
                return f1.foodItem.compareTo(f2.foodItem);
            }
            return Integer.compare(f2.rating, f1.rating);
        }
    }

    private static class Food {
        private String foodItem;
        private String cus;
        private int rating;

        Food(String food, int rating, String cus) {
            this.foodItem = food;
            this.rating = rating;
            this.cus = cus;
        }
    }
}

/*
 * 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);
 */