public int findCheapestPrice(int n, int[][] flights, int src, int dst, int k) {
        List<List<int[]>> adj = new ArrayList<>();
        for (int i = 0; i < n; i++) adj.add(new ArrayList<>());
        for (int[] flight : flights) {
            adj.get(flight[0]).add(new int[] {flight[1], flight[2]});
        }
        Queue<int[]> q = new LinkedList<>();
        q.offer(new int[] {src, 0});
        int[] minCost = new int[n];
        Arrays.fill(minCost, Integer.MAX_VALUE);
        int stops = 0;
        while (!q.isEmpty() && stops <= k) {
            int size = q.size();
            while (size-- > 0) {
                int[] curr = q.poll();
                for (int[] neighbour : adj.get(curr[0])) {
                    int price = neighbour[1], neighbourNode = neighbour[0];
                    if (price + curr[1] >= minCost[neighbourNode]) continue;
                    minCost[neighbourNode] = price + curr[1];
                    q.offer(new int[] {neighbourNode, minCost[neighbourNode]});
                }
            }
            stops++;
        }
        return minCost[dst] == Integer.MAX_VALUE ? -1 : minCost[dst];
    }