692. Top K Frequent Words

Top K Frequent Words - LeetCode

692. Top K Frequent Words

Medium

Given an array of strings words and an integer k, return the k most frequent strings.

Return the answer sorted by the frequency from highest to lowest. Sort the words with the same frequency by their lexicographical order.

Example 1:

Input: words = ["i","love","leetcode","i","love","coding"], k = 2
Output: ["i","love"]
Explanation: "i" and "love" are the two most frequent words.
Note that "i" comes before "love" due to a lower alphabetical order.

Example 2:

Input: words = ["the","day","is","sunny","the","the","the","sunny","is","is"], k = 4
Output: ["the","is","sunny","day"]
Explanation: "the", "is", "sunny" and "day" are the four most frequent words, with the number of occurrence being 4, 3, 2 and 1 respectively.

Constraints:

• 1 <= words.length <= 500
• 1 <= words[i].length <= 10
• words[i] consists of lowercase English letters.
• k is in the range [1, The number of **unique** words[i]]

Follow-up: Could you solve it in O(n log(k)) time and O(n) extra space?

중요한건 O(n log(k))이나 O(n)으로 해결해야 함

class Solution:
    def topKFrequent(self, words: List[str], k: int) -> List[str]:
        dic = {}
        for word in words:
            if word in dic:
                dic[word] -= 1
            else:
                dic[word] = -1

        heap = []
        for key, value in dic.items():
            heapq.heappush(heap, (value, key))

        res = []
        for i in range(0, k):
            item = heapq.heappop(heap)
            res.append(item[1])

        return res

일전에 풀었던 문제에서 아이디어를 착용해서 count를 -로 가져가는 방법으로 해결함

힙메모리에는 튜플타입으로 데이터를 넣어줌

튜플과 리스트의 차이는??