K’th largest element in a stream

'''
Logic:
take a min heap and push the element if size of min heap is less than k.
if min heap size is k so,kth maxium element will be at top of min heap
so if current element is smaller than top of min heap then it will not
contribute in kth maximum element else pop top element and push current
element at top.
every time kth maxiumum element will be at top if min heap size is k
'''
from heapq import heappush, heappop
class Solution:
    def kthLargest(self, arr, k):
        heap = []
        res = []

        for num in arr:
            if len(heap) < k:
                heappush(heap, num)
            elif num > heap[0]:
                heappop(heap)
                heappush(heap, num)

            if len(heap) < k:
                res.append(-1)
            else:
                res.append(heap[0])

        return res