findCheapestPrice = function (n, flights, src, dst, K) {
    const { graph, seen, minHeap } = buildGraph(n, flights, src, dst, K);

    return search(graph, src, dst, seen, minHeap);
}
@param {number} n
@param {number[][]} flights
@param {number} src
@param {number} dst
@param {number} k
@return {number}