215. Kth Largest Element in an Array

Medium


Given an integer array nums and an integer k, return the kth largest element in the array.

Note that it is the kth largest element in the sorted order, not the kth distinct element.

You must solve it in O(n) time complexity.

 

Example 1:

Input: nums = [3,2,1,5,6,4], k = 2
Output: 5

Example 2:

Input: nums = [3,2,3,1,2,4,5,5,6], k = 4
Output: 4

 

Constraints:

  • 1 <= k <= nums.length <= 105
  • -104 <= nums[i] <= 104




 class Solution:
    def findKthLargest(self, nums: List[int], k: int) -> int:

        #nums = [x*-1 for x in nums]
#         heapq.heapify(nums)

#         for i in range(len(nums)):
#             num = nums[0]
#             heapq.heappop(nums)

#             if i == k-1:
#                 return -num

        heap = nums[:k]
        heapq.heapify(heap)
        for num in nums[k:]:
            if num > heap[0]:
                heapq.heappushpop(heap, num)

        return heap[0]

Random Note


Floyd's Tortoise and Hare is used to detect linked list cycle.