543. Kth Largest in N Arrays

min heap, k elements. 可能是最简单的  hard 题目.

from heapq import heappush, heappop
class Solution:
    def KthInArrays(self, arrays, k):
        # init, min heap, negative.
        h = []

        for A in arrays:
            for v in A:
                if not h or len(h) <= k or v > h[0]:
                    heappush(h, v)
                if len(h) > k:
                    heappop(h)
        return h[0]