347. Top K Frequent Elements

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:

1 2	Input: nums = [1,1,1,2,2,3], k = 2 Output: [1,2]

Example 2:

1 2	Input: nums = [1], k = 1 Output: [1]

找list中個數k的數值，可以用python Counter.most_common，裡面是heapq.nlargest，所以時間複雜度是nlogn，找出符合各數的數字放進ret回傳。

T:O(nlogn), S:O(n)
from collections import Counter
class Solution(object):
    def topKFrequent(self, nums, k):
        if k == len(nums):return nums 
        count = Counter(nums).most_common(k) # (數字, 個數)
        ret = []
        for x,y in count:
            ret.append(x)
        return ret
或直接
return [x for x, y in collections.Counter(nums).most_common(k)]

如果你覺得這篇文章很棒，請你不吝點讚 (ﾟ∀ﾟ)