Cheapest Flights Within K Stops

class Solution:
    def findCheapestPrice(self, n: int, flights: List[List[int]], src: int, dst: int, k: int) -> int:
        graph = [[] for i in range(n)]
        for frm, to, cost in flights:
            graph[frm].append((cost, to))
        
        heap = [(0, 0, src)]
        heapq.heapify(heap)
        costs_and_stops = [(float("infinity"), float("infinity"))] * n
        costs_and_stops[src] = (0, 0)
        
        while heap:
            cost, stops, x = heapq.heappop(heap)
            if x == dst:
                return cost
            if stops <= k:
                for next_cost, next_stop in graph[x]:
                    if costs_and_stops[next_stop][0] > next_cost + cost or costs_and_stops[next_stop][1] > stops + 1:
                        costs_and_stops[next_stop] = (next_cost + cost, stops + 1)
                        heapq.heappush(heap, (cost + next_cost, stops + 1, next_stop))
        
        return -1