2353. Design a Food Rating System

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# 題目敘述

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.

# 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".

# 解題思路

# Solution

import java.util.Comparator;

import java.util.HashMap;

import java.util.Map;

import java.util.PriorityQueue;

class FoodRatings {

    public class Data {

        String food;

        String cuisine;

        int rating;

        public Data(String food, String cuisine, int rating) {

            this.food = food;

            this.cuisine = cuisine;

            this.rating = rating;

        }

    }

    Map<String, PriorityQueue<Data>> cuisineMap;

    Map<String, Data> foodMap;

    public FoodRatings(String[] foods, String[] cuisines, int[] ratings) {

        cuisineMap = new HashMap<>();

        foodMap = new HashMap<>();

        for (int i = 0; i < foods.length; i++) {

            Data data = new Data(foods[i], cuisines[i], ratings[i]);

            foodMap.put(foods[i], data);

            if (cuisineMap.containsKey(cuisines[i])) {

                cuisineMap.get(cuisines[i]).add(data);

            } else {

                PriorityQueue<Data> pq = new PriorityQueue<Data>(new Comparator<Data>() {

                    @Override

                    public int compare(Data a, Data b) {

                        int result = b.rating - a.rating;

                        if (result == 0) {

                            return (a.food).compareTo(b.food);

                        }

                        return result;

                    }

                });

                pq.add(data);

                cuisineMap.put(cuisines[i], pq);

            }

        }

    }

    public void changeRating(String food, int newRating) {

        Data prev = foodMap.get(food);

        cuisineMap.get(prev.cuisine).remove(prev);

        Data curr = new Data(food, prev.cuisine, newRating);

        foodMap.put(food, curr);

        cuisineMap.get(prev.cuisine).add(curr);

    }

    public String highestRated(String cuisine) {

        return cuisineMap.get(cuisine).peek().food;

    }

}

/**

 * 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);

 */