Submission #1238223

#	Time	Username	Problem	Language	Result	Execution time	Memory
1238223		Timosh	통행료 (IOI18_highway)	C++20	51 / 100	313 ms	327680 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);
  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 dfs = [&](auto dfs, int node, int par) -> void
  {
    for (auto &x : g[node])
    {
      if (x == par)
        continue;
      d[x] = d[node] + 1;
      dfs(dfs, x, node);
    }
  };
  dfs(dfs, 0, -1);
  int a = 0;
  int l = 0, r = N;
  while (l <= r)
  {
    int m = (l + r) / 2;
    for (int i = 0; i < M; i++)
      w[i] = max(d[U[i]], d[V[i]]) > m;
    int x = ask(w);
    if (x == D)
      r = m - 1;
    else
      a = m, l = m + 1;
  }
  a++;
  vector<int> cands;
  for (int i = 0; i < M; i++)
    if (max(d[U[i]], d[V[i]]) == a)
      cands.push_back(i);
  while (cands.size() > 1)
  {
    int m = cands.size() / 2;
    for (auto &i : w)
      i = 0;
    for (int j = 0; j < m; j++)
      w[cands[j]] = 1;
    int x = ask(w);
    vector<int> R;
    while (cands.size() > m)
      R.push_back(cands.back()), cands.pop_back();
    if (x == D)
      cands = R;
  }
  int b = (d[V[cands[0]]] > d[U[cands[0]]] ? V[cands[0]] : U[cands[0]]);
  d[b] = 0;
  a = l = 0, r = M - 1;
  dfs(dfs, b, -1);
  vector<int> p(M + 1);
  iota(p.begin(), p.end(), 0ll);
  sort(p.begin(), p.end(), [&](int &i, int &j)
       { return max(d[U[i]], d[V[i]]) < max(d[U[j]], d[V[j]]); });
  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: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 6 / 6
• Subtask 4: 33 / 33
• Subtask 5: 0 / 18
• Subtask 6: 0 / 31