Submission #607588

#	Time	Username	Problem	Language	Result	Execution time	Memory
607588		evenvalue	Highway Tolls (IOI18_highway)	C++17	51 / 100	170 ms	15996 KiB

highway

#include "highway.h"
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T>
using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;

template<typename T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;
template<typename T>
using max_heap = priority_queue<T, vector<T>, less<T>>;

using int64 = long long;
using ld = long double;

constexpr int kInf = 1e9 + 10;
constexpr int64 kInf64 = 1e15 + 10;
constexpr int kMod = 1e9 + 7;

void tree_subtasks(const int n, const vector<int> &u, const vector<int> &v, const int a, const int b) {
  const int m = u.size();
  vector<int> w(m);
  int64 all_0 = ask(w);
  int lo = 0, hi = m - 1;
  while (lo < hi) {
    const int mid = (lo + hi) / 2;
    fill(w.begin() + mid + 1, w.begin() + hi + 1, 1);
    const int64 this_query = ask(w);
    fill(w.begin() + mid + 1, w.begin() + hi + 1, 0);
    if (this_query > all_0) {
      lo = mid + 1;
    } else {
      hi = mid;
    }
  }

  vector<vector<pair<int, int>>> g(n);
  for (int i = 0; i < m; i++) {
    const int x = u[i], y = v[i];
    g[x].emplace_back(y, i);
    g[y].emplace_back(x, i);
  }

  auto find_s_t = [&](const int s, const int p) {
    vector<int> w(m);

    function<void(int, int)> dfs1 = [&](const int x, const int p) {
      for (const auto &[y, i] : g[x]) {
        if (y == p) continue;
        w[i] = 1;
        dfs1(y, x);
      }
    };
    dfs1(s, p);
    const int64 this_1 = ask(w);
    const int depth = (this_1 - all_0) / (b - a);

    if (depth == 0) {
      return s;
    }

    vector<pair<int, int>> candidates;
    function<void(int, int, int, int)> dfs2 = [&](const int x, const int par, const int d, const int idx) {
      if (d == depth) {
        candidates.emplace_back(x, idx);
        return;
      }
      for (const auto &[y, i] : g[x]) {
        if (y == par) continue;
        dfs2(y, x, d + 1, i);
      }
    };
    dfs2(s, p, 0, -1);

    fill(w.begin(), w.end(), 0);

    int lo = 0, hi = (int) candidates.size() - 1;
    while (lo < hi) {
      const int mid = (lo + hi) / 2;
      for (int i = lo; i <= mid; i++) {
        w[candidates[i].second] = 1;
      }
      for (int i = mid + 1; i <= hi; i++) {
        w[candidates[i].second] = 0;
      }
      if (ask(w) > all_0) {
        hi = mid;
      } else {
        lo = mid + 1;
      }
    }
    return candidates[lo].first;
  };
  answer(find_s_t(u[lo], v[lo]),
         find_s_t(v[lo], u[lo]));
}

void subtask5(const int n, const vector<int> &u, const vector<int> &v, const int a, const int b) {
  const int m = u.size();

  auto different_sets = [&](const vector<int> &partition)-> bool {
    static vector<int> w(m);
    for (int i = 0; i < n; i++) {
      w[i] = (partition[u[i]] == partition[v[i]]);
    }
    return (ask(w) & 1);
  };

  int xor_st = 0;
  vector<int> partition(n), zeros;
  for (int bit = 0; bit < 20; bit++) {
    for (int i = 0; i < n; i++) {
      partition[i] = (i & (1 << bit));
    }
    const int c = different_sets(partition);
    if (xor_st == 0 and c == 1) {
      for (int i = 0; i < n; i++) {
        if (partition[i]) continue;
        zeros.push_back(i);
      }
    }
    xor_st += c * (1 << bit);
  }

  int lo = 0, hi = zeros.size() - 1;
  fill(partition.begin(), partition.end(), 1);
  for (const int x : zeros) {
    partition[x] = 0;
  }
  while (lo < hi) {
    const int mid = (lo + hi) / 2;
    for (int i = lo; i <= mid; i++) {
      partition[i] = 0;
    }
    for (int i = mid + 1; i <= hi; i++) {
      partition[i] = 1;
    }
    if (different_sets(partition)) {
      hi = mid;
    } else {
      lo = mid + 1;
    }
  }
  answer(lo, lo ^ xor_st);
}

void find_pair(const int n, const vector<int> u, const vector<int> v, const int a, const int b) {
  const int m = u.size();
  if (m == n - 1) tree_subtasks(n, u, v, a, b);
  else if (a == 1 and b == 2) subtask5(n, u, v, a, b);
  else assert(false);
}

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