1function minimumFuelCost(roads, seats) {
2    const adjList = new Map();
3    const visited = new Set();
4
5    function dfs(node) {
6        visited.add(node);
7        let representatives = 1;
8        for (let neighbor of (adjList.get(node) || [])) {
9            if (!visited.has(neighbor)) {
10                const reps = dfs(neighbor);
11                cost += Math.ceil(reps / seats);
12                representatives += reps;
13            }
14        }
15        return representatives;
16    }
17
18    for (const [a, b] of roads) {
19        if (!adjList.has(a)) adjList.set(a, []);
20        if (!adjList.has(b)) adjList.set(b, []);
21        adjList.get(a).push(b);
22        adjList.get(b).push(a);
23    }
24
25    let cost = 0;
26    dfs(0);
27    return cost;
28}
29
30const roads = [[3,1],[3,2],[1,0],[0,4],[0,5],[4,6]];
31const seats = 2;
32console.log(minimumFuelCost(roads, seats));

1using System.Collections.Generic;

class Solution {
    public static long MinimumFuelCost(int[][] roads, int seats) {
        int n = roads.Length + 1;
        List<int>[] adjList = new List<int>[n];
        for (int i = 0; i < n; ++i) adjList[i] = new List<int>();
        foreach (var road in roads) {
            adjList[road[0]].Add(road[1]);
            adjList[road[1]].Add(road[0]);
        }

        bool[] visited = new bool[n];
        Queue<(int node, int reps)> q = new Queue<(int, int)>();
        q.Enqueue((0, 0));
        visited[0] = true;
        long cost = 0;

        while (q.Count > 0) {
            var (node, reps) = q.Dequeue();
            int max_reps = reps + 1;
            long nodeFuel = (max_reps + seats - 1) / seats;
            cost += nodeFuel;
            foreach (int neighbor in adjList[node]) {
                if (!visited[neighbor]) {
                    visited[neighbor] = true;
                    q.Enqueue((neighbor, max_reps));
                }
            }
        }

        return cost;
    }

    static void Main() {
        int[][] roads = { new int[]{0,1}, new int[]{0,2}, new int[]{0,3} };
        int seats = 5;
        Console.WriteLine(MinimumFuelCost(roads, seats));
    }
}