問題: atcoder.jp 解答: #include <bits/stdc++.h> #include <algorithm> #define rep(i, n) for(int i=0; i<(n); ++i) using namespace std; int main(){ int n; cin >> n; map<int, vector<int>> to; rep(i,n){ int a, b; cin >> a >> b; to[a].push_back(b); to[b].push_back(a); } set<int> reach; queue<int> </int></int></int,></algorithm></bits/stdc++.h>…