範例程式碼 uva11518

//uva11518
#include <iostream>
#include <vector>
#include <queue>
using namespace std;

int knockDown(int from, int down[], vector<vector<int> > &road){

    int count = 0;
    queue<int> q;
    
    // start bfs
    q.push(from);
    while (!q.empty()){
        int len = q.size();
        for (int i = 1; i <= len; i++){
            int domino = q.front();
            if (!down[domino]){
                for (int j = 0; j < road[domino].size(); j++)
                    q.push(road[domino][j]);
                down[domino] = 1;
                count++;
            }
            q.pop();
        }
    }
    return count;
}


int main() {
    int t, n, m, l;
    cin >> t;

    while(t--){
        int from, to;
        vector<vector<int> > road(10001);
       
        cin >> n >> m >> l;
        for (int i = 1; i <= m; i++){
            cin >> from >> to;
            road[from].push_back(to);
        }

        int down[10001] = {0}, total = 0;
        for (int i = 1; i <= l; i++){
            cin >> from;
            //cout << knockDown(from, down, road) << "\n";
            total += knockDown(from, down, road);
        }
        cout << total << "\n";
    }
}