바이러스

#include <iostream> #include <vector> int N, M; std::vector<int> computer[101]; bool visited[101]; int ans = 0; void io_faster() { std::ios_base::sync_with_stdio(false); std::cin.tie(0); std::cout.tie(0); } void input() { int a, b; io_faster(); std::cin >> N >> M; for (int i = 0 ; i < M ; i++) { std::cin >> a >> b; computer[a].push_back(b); computer[b].push_back(a); } } void dfs(int node) { int size = computer[node].size(); for (int i = 0 ; i < size ; i++) { if (visited[computer[node][i]]) continue; visited[computer[node][i]] = 1; ans++; dfs(computer[node][i]); } } void solve() { visited[1] = 1; dfs(1); } void print_val() { std::cout << ans; } int main() { input(); solve(); print_val(); return (0); }