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2353-design-a-food-rating-system.rb
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# frozen_string_literal: true
# 2353. Design a Food Rating System
# Medium
# https://leetcode.com/problems/design-a-food-rating-system
=begin
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".
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.
=end
class FoodRatings
def initialize(f, c, r)
@c, @f = {}, {}
f.each_with_index do | f, i |
@f[f] = [c[i], -r[i]]
@c[c[i]] ||= CRBTreeMap.new
@c[c[i]].push [-r[i], f], true
end
end
def change_rating(f, n)
c, p = @f[f]
n = -n
if p != n
@f[f] = [c, n]
@c[c].delete [p, f]
@c[c].push [n, f], true
end
end
def highest_rated(c)
@c[c].min_key.last
end
end
# Your FoodRatings object will be instantiated and called as such:
# obj = FoodRatings.new(foods, cuisines, ratings)
# obj.change_rating(food, new_rating)
# param_2 = obj.highest_rated(cuisine)