Submission #778121

#	Time	Username	Problem	Language	Result	Execution time	Memory
778121		NeroZein	Highway Tolls (IOI18_highway)	C++17	5 / 100	194 ms	262144 KiB

highway

#include "highway.h"
#include "bits/stdc++.h"
using namespace std; 
 
int n, m;
vector<int> pe;
vector<int> dep;
vector<vector<pair<int,int>>> g; 
 
void Dfs (int v, int p) {
  for (auto [u, i] : g[v]) {
    if (u == p) {
      continue;
    }
    pe[u] = i; 
    dep[u] = dep[v] + 1; 
    Dfs(u, v); 
  }
}
 
void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B) {
  n = N;
  g.resize(n); 
  pe.resize(n); 
  dep.resize(n); 
  m = (int) U.size(); 
  for (int i = 0; i < m; ++i) {
    g[U[i]].push_back({V[i], i});
    g[V[i]].push_back({U[i], i});
  }
  Dfs(0, 0); 
  vector<int> vec; 
  vector<int> w(m, 0); 
  int dis = ask(w); 
  int depT = dis / A;
  assert(depT != 0); 
  for (int i = 0; i < n; ++i) {
    if (dep[i] == depT) {
      vec.push_back(i); 
    }
  }
  auto fix = [&](vector<int> nodes) {
    vector<int> ret(m);
    for (int u : nodes) {
      assert(u != 0);
      ret[pe[u]] = true; 
    }
    return ret;
  }; 
  while (vec.size() > 1) {
    vector<int> lx, rx;
    int mid = (int) vec.size() / 2;
    for (int i = 0; i < mid; ++i) {
      lx.push_back(vec[i]);
    }
    for (int i = mid; i < (int) vec.size(); ++i) {
      rx.push_back(vec[i]); 
    }
    if (ask(fix(lx)) > dis) {
      vec = lx;
    } else {
      vec = rx; 
    }
  }
  assert(!vec.empty());
  answer(0, vec[0]);//S, T
}

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