LeetCode-in-All
347. Top K Frequent Elements
Medium
Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order.
Example 1:
Input: nums = [1,1,1,2,2,3], k = 2
Output: [1,2]
Example 2:
Input: nums = [1], k = 1
Output: [1]
Constraints:
1 <= nums.length <= 105kis in the range[1, the number of unique elements in the array].- It is guaranteed that the answer is unique.
Follow up: Your algorithm’s time complexity must be better than O(n log n), where n is the array’s size.
Solution
import heapq
from collections import Counter
class Solution:
def topKFrequent(self, nums: List[int], k: int) -> List[int]:
# Count the frequency of each number
freq_map = Counter(nums)
# Create a min heap to store the top k elements
min_heap = []
for num, freq in freq_map.items():
heapq.heappush(min_heap, (freq, num))
if len(min_heap) > k:
heapq.heappop(min_heap)
# Extract the elements from the heap
result = []
while min_heap:
result.append(heapq.heappop(min_heap)[1])
# Return the result in descending order of frequency
return result[::-1]