Submission #923214

#	Time	Username	Problem	Language	Result	Execution time	Memory
923214		Ianis	Easter Eggs (info1cup17_eastereggs)	C++17	100 / 100	23 ms	1020 KiB

eastereggs

#include <bits/stdc++.h>
#include "grader.h"

using namespace std;

using pii = pair<int, int>;

bool my_query(const set<int> &s) {
   if (s.empty()) return 0;
   vector<int> v;
   for (auto &it : s)
      v.push_back(it);
   return query(v);
}

int findEgg(int n, vector<pii> bridges) {
   vector<vector<int>> g(n + 1);
   vector<bool> vis(n + 1);
   vector<int> euler;
   vector<int> in;

   for (auto [ x, y ] : bridges) {
      g[x].push_back(y);
      g[y].push_back(x);
   }

   function<void(int)> dfs = [&](int x) {
      vis[x] = true;

      in.push_back(int(euler.size()));
      euler.push_back(x);

      for (auto u : g[x]) {
         if (!vis[u]) {
            dfs(u);
            euler.push_back(x);
         }
      }
   };

   dfs(1);

   function<bool(int)> check = [&](int mid) {
      set<int> s;
      for (int i = 0; i <= in[mid]; i++)
         s.insert(euler[i]);
      return my_query(s);
   };

   int mask = 0;

   for (int i = log2(in.size()); i >= 0; i--) {
      mask |= 1 << i;
      if (mask >= int(in.size()) || check(mask - 1)) mask ^= 1 << i;
   }

   return euler[in[mask]];
}

• Subtask 1: 40 / 40
• Subtask 2: 40 / 40
• Subtask 3: 20 / 20