#include<bits/stdc++.h> using namespace std; #define pb push_back vector<vector<int>> create_map(int n, int m, vector<int> a, vector<int> b) { vector<vector<int>> graph(n+1); for (int i = 0; i < m; i++) { graph[a[i]].pb(b[i]); graph[b[i]].pb(a[i]); } vector<int> line; vector<vector<bool>> con(n+1, vector<bool> (n+1, false)); auto dfs = [&](auto &dfs, int u) -> void { line.pb(u); for (int e : graph[u]) if (!con[u][e]) { con[u][e] = true; con[e][u] = true; dfs(dfs, e); line.pb(u); } }; dfs(dfs, 1); vector<vector<int>> map(line.size(), line); return map; }