백준 2606번 - 바이러스 (C++)

문제

#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;
 
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
 
    int Num, Link_Num, ans = 0;
    cin >> Num >> Link_Num;
    queue<int> Que;
    vector<bool> Vec_Check(Num + 1, false);
    vector<pair<int, int>> Vec(Link_Num * 2 + 1);
 
    for (int i = 0; i < Link_Num * 2; i += 2)
    {
        cin >> Vec[i].first >> Vec[i].second;
        Vec[i + 1].first = Vec[i].second;
        Vec[i + 1].second = Vec[i].first;
    }
 
    //Bfs
    Que.push(1);
    Vec_Check[Que.front()] = true;
    while (!Que.empty())
    {
        for (auto& itor : Vec)
        {
            if (itor.first == Que.front() && !Vec_Check[itor.second])
            {
                Vec_Check[itor.second] = true;
                Que.push(itor.second);
                ++ans;
            }
        }
        Que.pop();
    }
 
    cout << ans;
}