Submission #952493

#	Time	Username	Problem	Language	Result	Execution time	Memory
952493		kilkuwu	Easter Eggs (info1cup17_eastereggs)	C++17	0 / 100	3 ms	512 KiB

eastereggs

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

using namespace std;

int findEgg(int N, vector < pair < int, int > > bridges);
int query(vector < int > islands);
#endif

int findEgg (int N, vector<pair<int, int>> bridges) {
  std::vector<std::vector<int>> adj(N + 1);

  for (auto bridge : bridges) {
    int u, v;
    std::tie(u, v) = bridge;
    adj[u].push_back(v);
    adj[v].push_back(u);
  }

  std::vector<int> maybe(N + 1, 1);

  // bfs and take half each time

  int num_candidates = N;
  while (num_candidates > 1) {
    std::vector<int> to_query;
    std::vector<int> inside(N + 1);
    int target = num_candidates / 2;
    std::function<void(int, int)> dfs = [&](int u, int p) -> void {
      to_query.push_back(u);
      target -= maybe[u];
      inside[u] = 1;
      if (target == 0) {
        return;
      }

      for (int v : adj[u]) {
        if (v == p) continue;
        dfs(v, u);
      }
    };

    dfs(1, 1);

    int res = query(to_query);
    if (res == 1) {
      num_candidates = 0;
      for (int i = 1; i <= N; i++) {
        if (!inside[i]) {
          maybe[i] = 0;
        }
        num_candidates += maybe[i];
      }
    } else {
      num_candidates = 0;
      for (int i = 1; i <= N; i++) {
        if (inside[i]) {
          maybe[i] = 0;
        }
        num_candidates += maybe[i];
      }
    }
  }

  for (int i = 1; i <= N; i++) {
    if (maybe[i]) return i;
  }

  assert(false);
}

• Subtask 1: 0 / 40
• Subtask 2: 0 / 40
• Subtask 3: 0 / 20