668 - heap

class Solution:
    def findKthNumber(self, m: int, n: int, k: int) -> int:

        h = [(i, i) for i in range(1, m+1)]
        heapq.heapify(h)

        while k:
            val, i = heapq.heappop(h)
            if val // i < n:
                heapq.heappush(h, ((val // i + 1) * i, i))
            k -= 1

        return val