Cheapest Flights Within K Stops LeetCode solution in Python

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class Solution:
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    def findCheapestPrice(
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        self, n: int, flights: List[List[int]], src: int, dst: int, k: int
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    ) -> int:
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        graph = defaultdict(list)
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        for u, v, w in flights:
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            graph[u].append((v, w))
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        pq = [(0, src, 0)]
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        dis = [float("inf")] * n
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        while pq:
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            c, n, l = heappop(pq)
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            if n == dst:
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                return c
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            if l > k or l >= dis[n]:
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                continue
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            dis[n] = l
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            for v, w in graph[n]:
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                heappush(pq, (c + w, v, l + 1))
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        return -1