from collections import deque

class Solution:
    def findCheapestPrice(self, n: int, flights: List[List[int]], src: int, dst: int, k: int) -> int:
        g = [[] for _ in range(n)]
        for flight in flights:
            g[flight[0]].append((flight[1],flight[2]))
        q = deque([(src,0,0)])
        path = [float('inf')]*n
        path[src] = 0
        while q:
            cur,stops,price = q.popleft()

            if stops < k+1:
                for nex,cost in g[cur]:
                    if price + cost < path[nex]:
                        path[nex] = price+cost
                        q.append((nex,stops+1,price+cost))

        return -1 if path[dst] == float('inf') else path[dst]