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cutVertex.cpp
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cutVertex.cpp
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//
// Created by 문다훈 on 2023/11/28.
//
#include <bits/stdc++.h>
using namespace std;
int pre[10001];
int c = 0;
vector<vector<int>> adj;
set<int> cut_vertexes;
int dfs(vector<vector<int>> adj, set<int>& cv, int curV, int parent) {
pre[curV] = ++c;
int ret = pre[curV];
int child_n = 0;
for(auto& next : adj[curV]) {
if(!pre[next]) {
child_n++;
int low = dfs(adj, cv, next ,curV);
if(parent != 0 && low >= pre[curV]) {
cv.insert(curV);
}
ret = min(ret, low);
} else {
ret = min(ret, pre[next]);
}
}
if(parent == 0 && child_n >1) {
cv.insert(curV);
}
return ret;
}
int main(void) {
int N, E;
cin >> N >> E;
adj.resize(N+1);
// Tree -> undirected connected acyclic graph
for(int i = 0; i < E; i++) {
int src, dst;
cin >> src >> dst;
adj[src].push_back(dst);
adj[dst].push_back(src);
}
// find cut vertex.
// 1. find root
for(int i = 1; i <= N; i++) {
if(!pre[i]) {
dfs(adj, cut_vertexes, i, 0);
}
}
cout << cut_vertexes.size() << '\n';
for(auto n : cut_vertexes) {
cout << n << " ";
}
return 0;
}