연결 요소의 개수

#include <iostream> #include <vector> size_t N, M; std::vector<std::vector<int> >graph; bool visited[1001]; int ans; void input_faster() { std::ios_base::sync_with_stdio(false); std::cin.tie(0); std::cout.tie(0); } void input() { int a, b; input_faster(); std::cin >> N >> M; graph.resize(N + 1); for (size_t i = 0 ; i < M ; i++) { std::cin >> a >> b; graph[a].push_back(b); graph[b].push_back(a); } } void dfs(int i) { for (size_t j = 0 ; j < graph[i].size(); j++) { if (visited[graph[i][j]]) continue; visited[graph[i][j]] = 1; dfs(graph[i][j]); } } void solve() { for (size_t i = 1 ; i <= N ; i++) { if (visited[i]) continue; ans++; visited[i] = 1; dfs(i); } } void print_val() { std::cout << ans; } int main() { input(); solve(); print_val(); return (0); }