Submission #1238247

#	Time	Username	Problem	Language	Result	Execution time	Memory
1238247		Timosh	Highway Tolls (IOI18_highway)	C++20	46 / 100	102 ms	9520 KiB

highway

#include "bits/stdc++.h"
#include "highway.h"

using namespace std;

void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B)
{
  int M = U.size();
  vector<int> d(N), w(M);
  vector<int> p(M + 1);
  iota(p.begin(), p.end(), 0ll);
  int D = ask(w);
  vector<vector<int>> g(N);
  for (int i = 0; i < M; i++)
  {
    g[U[i]].push_back(V[i]);
    g[V[i]].push_back(U[i]);
  }
  auto bfs = [&](int node) -> void
  {
    queue<int> q;
    q.push(node);
    d[node] = 0;
    vector<int> vis(N);
    vis[node] = 1;
    while (!q.empty())
    {
      int cur = q.front();
      q.pop();
      for (auto &x : g[cur])
      {
        if (vis[x])
          continue;
        vis[x] = 1;
        d[x] = d[cur] + 1;
        q.push(x);
      }
    }
  };
  bfs(0);
  sort(p.begin(), p.end(), [&](int &i, int &j)
       { return max(d[U[i]], d[V[i]]) < max(d[U[j]], d[V[j]]); });
  int a = 0;
  int l = 0, r = M - 1;
  while (l <= r)
  {
    int m = (l + r) / 2;
    for (int i = 0; i < M; i++)
      w[p[i]] = (i >= m);
    int x = ask(w);
    if (x == D)
      r = m - 1;
    else
      l = m + 1, a = p[m];
  }
  int b = (d[V[a]] > d[U[a]] ? V[a] : U[a]);
  bfs(b);
  sort(p.begin(), p.end(), [&](int &i, int &j)
       { return max(d[U[i]], d[V[i]]) < max(d[U[j]], d[V[j]]); });
  a = l = 0, r = M - 1;
  while (l <= r)
  {
    int m = (l + r) / 2;
    for (int i = 0; i < M; i++)
      w[p[i]] = (i >= m);
    int x = ask(w);
    if (x == D)
      r = m - 1;
    else
      l = m + 1, a = p[m];
  }
  int c = (d[V[a]] > d[U[a]] ? V[a] : U[a]);
  answer(c, b);
}

• Subtask 1: 0 / 5
• Subtask 2: 7 / 7
• Subtask 3: 6 / 6
• Subtask 4: 33 / 33
• Subtask 5: 0 / 18
• Subtask 6: 0 / 31