378. Kth Smallest Element in a Sorted Matrix

Python

Min Heap

• Time: O(N*M)
• Space: O(N*M)

import heapq


class Solution:
    def kthSmallest(self, matrix: List[List[int]], k: int) -> int:
        heap = []
        for row in matrix:
            for num in row:
                heapq.heappush(heap, num)

        return heapq.nsmallest(k, heap)[-1]