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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. #ifdef LOCAL
  5. #define DEBUG(...) debug(#__VA_ARGS__, __VA_ARGS__)
  6. #else
  7. #define DEBUG(...) 6
  8. #endif
  9.  
  10. template<typename T, typename S> ostream& operator << (ostream &os, const pair<T, S> &p) {return os << "(" << p.first << ", " << p.second << ")";}
  11. template<typename C, typename T = decay<decltype(*begin(declval<C>()))>, typename enable_if<!is_same<C, string>::value>::type* = nullptr>
  12. ostream& operator << (ostream &os, const C &c) {bool f = true; os << "["; for (const auto &x : c) {if (!f) os << ", "; f = false; os << x;} return os << "]";}
  13. template<typename T> void debug(string s, T x) {cerr << s << " = " << x << "\n";}
  14. template <typename T, typename... Args> void debug(string s, T x, Args... args) {for (int i=0, b=0; i<(int)s.size(); i++) if (s[i] == '(' || s[i] == '{') b++; else
  15. if (s[i] == ')' || s[i] == '}') b--; else if (s[i] == ',' && b == 0) {cerr << s.substr(0, i) << " = " << x << " | "; debug(s.substr(s.find_first_not_of(' ', i + 1)), args...); break;}}
  16.  
  17. int main() {
  18.     ios_base::sync_with_stdio(false);
  19.     cin.tie(NULL);
  20.  
  21.     mt19937 rng((uint32_t) chrono::steady_clock::now().time_since_epoch().count());
  22.     // mt19937 rng(6);
  23.  
  24.     int n, m;
  25.     cin >> n >> m;
  26.     vector<vector<int>> adj(n);
  27.     vector<vector<bool>> mat(n, vector<bool>(n));
  28.     for (int i=0; i<m; i++) {
  29.         int u, v;
  30.         cin >> u >> v;
  31.         u--, v--;
  32.         adj[u].push_back(v);
  33.         adj[v].push_back(u);
  34.         mat[u][v] = mat[v][u] = true;
  35.     }
  36.  
  37.     if (n <= 20) {
  38.         auto solve = [&] (auto &self, int u, int mask) -> bool {
  39.             if (mask == (1 << n) - 1) {
  40.                 if (u == 0) {
  41.                     cout << u + 1 << " ";
  42.                     return true;
  43.                 }
  44.                 return false;
  45.             }
  46.             for (int v : adj[u])
  47.                 if (~mask & (1 << v) && self(self, v, mask | (1 << v))) {
  48.                     cout << u + 1 << " ";
  49.                     return true;
  50.                 }
  51.             return false;
  52.         };
  53.         solve(solve, 0, 0);
  54.         cout << "\n";
  55.         return 0;
  56.     }
  57.  
  58.     for (int rep=0; rep<100; rep++) {
  59.         vector<int> ret(n);
  60.         iota(ret.begin() + 1, ret.end(), 1);
  61.         shuffle(ret.begin() + 1, ret.end(), rng);
  62.         ret.push_back(0);
  63.         bool done = false;
  64.         if (rep == 99)
  65.             done = true;
  66.         while (!done) {
  67.             done = true;
  68.             for (int i=0; i<n; i++)
  69.                 if (!mat[ret[i]][ret[i+1]]) {
  70.                     bool ok = false;
  71.                     for (int j=i+1; j<n; j++)
  72.                         if (mat[ret[j]][ret[j+1]] && mat[ret[i]][ret[j]] && mat[ret[i+1]][ret[j+1]]) {
  73.                             reverse(ret.begin() + i + 1, ret.begin() + j + 1);
  74.                             ok = true;
  75.                             break;
  76.                         }
  77.                     if (!ok) {
  78.                         for (int j=0; j+1<i; j++)
  79.                             if (mat[ret[j]][ret[j+1]] && mat[ret[i]][ret[j]] && mat[ret[i+1]][ret[j+1]]) {
  80.                                 int l = i + 1, r = j;
  81.                                 vector<bool> vis(n);
  82.                                 while (!vis[l] && !vis[r]) {
  83.                                     swap(ret[l], ret[r]);
  84.                                     vis[l] = vis[r] = true;
  85.                                     if (++l == n)
  86.                                         l = 0;
  87.                                     if (--r == -1)
  88.                                         r = n - 1;
  89.                                 }
  90.                                 ret[n] = ret[0];
  91.                                 ok = true;
  92.                                 break;
  93.                             }
  94.                         if (!ok)
  95.                             goto fail;
  96.                     }
  97.                     done = false;
  98.                 }
  99.         }
  100.         for (int i=0; i<=n; i++)
  101.             cout << ret[i] + 1 << " ";
  102.         cout << "\n";
  103.         return 0;
  104.         fail:;
  105.     }
  106.  
  107.     return 0;
  108. }
  109.  
Success #stdin #stdout 0s 5064KB
comments (?)
stdin 
Standard input is empty
stdout 
1
https://ideone.com/rIeQ5B
language:
C++14 (clang 8.0)
created:
3 years ago
visibility:
secret

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