Submission #573907

#	Time	Username	Problem	Language	Result	Execution time	Memory
573907		lumibons	Flight to the Ford (BOI22_communication)	C++17	46.67 / 100	4705 ms	1988 KiB

communication

#include <vector>
#include "communication.h"

typedef long long ll;

using namespace std;

struct interval {
  ll l, r;
  interval(ll l, ll r) : l(l), r(r) {}
  bool contains(ll x) {
    return l <= x && x < r;
  }
  ll length() {
    return r - l;
  }
  interval shrink(ll o, ll s) {
    return interval(min(r, l + o), min(r, l + o + s));
  }
};

vector<interval> splitIntervals(vector<interval> c, ll o, ll s) {
  vector<interval> r;
  for (interval &it : c) {
    if (s > 0 && it.length() - o > 0)
      r.push_back(it.shrink(o, s));
    s -= max(0LL, min(s, it.length() - o));
    o -= min(o, it.length());
  }
  return r;
}

bool contains(vector<interval> c, ll x) {
  for (interval &it : c)
    if (it.contains(x))
      return true;
  return false;
}

struct state {
  ll s = 0;
  vector<interval> c;
  state() {}
  state(ll N): s(N) {
    c.emplace_back(1, N + 1);
  }
  state(vector<vector<interval>> &cs) {
    for (vector<interval> &c : cs)
      add(c);
  }
  void add(interval it) {
    s += it.length();
    c.push_back(it);
  }
  void add(vector<interval> &c) {
    for (interval &it : c)
      add(it);
  }
  vector<vector<interval>> split() {
    vector<vector<interval>> r;
    ll s1 = s / 3, s2 = (s - s1) / 2, s3 = s - s1 - s2;
    r.push_back(splitIntervals(c, 0, s1));
    r.push_back(splitIntervals(c, s1, s2));
    r.push_back(splitIntervals(c, s1 + s2, s3));
    return r;
  }
  ll size() {
    return s;
  }
  vector<ll> remaining() {
    vector<ll> r;
    for (interval &it : c)
      for (ll v = it.l; v < it.r; v++)
        r.push_back(v);
    return r;
  }
};

std::pair<int, int> solve(int N, int X = -1) {
  state s(N);
  while (s.size() > 2) {
    vector<vector<interval>> c = s.split();
    int b1 = 1, b2;
    for (int i = 0; i < 2 && b1; i++)
      b1 = X != -1 ? send(contains(c[0], X) || contains(c[1], X)) : receive();
    if (!b1)
      b2 = X != -1 ? send(contains(c[0], X)) : receive();
    c.erase(c.begin() + (b1 ? 2 : (b2 ? 1 : 0)));
    s = state(c);
  }

  vector<ll> r = s.remaining();
  return {r[0], r.back()};
}

void encode(int N, int X) {
  solve(N, X);
}

std::pair<int, int> decode(int N) {
  return solve(N);
}

• Subtask 1: 15 / 15
• Subtask 2: 31.666665000000002 / 85