Submission #996350

#	Time	Username	Problem	Language	Result	Execution time	Memory
996350		MilosMilutinovic	Longest Trip (IOI23_longesttrip)	C++17	100 / 100	12 ms	612 KiB

longesttrip

#include "longesttrip.h"
#include <bits/stdc++.h>

using namespace std;

mt19937 rng(time(0));

vector<int> longest_trip(int n, int d) {
  auto Ask = [&](vector<int> a, vector<int> b) {
    return are_connected(a, b);
  }; 
  vector<int> idx(n);
  iota(idx.begin(), idx.end(), 0);
  shuffle(idx.begin(), idx.end(), rng);
  vector<int> pa, pb;
  pa.push_back(idx[0]);
  pb.push_back(idx[1]);
  bool know = false;
  for (int ver = 2; ver < n; ver++) {
    int i = idx[ver];
    if (know) {
      if (Ask({i}, {pa.back()})) {
        pa.push_back(i);
        know = false;
        continue;
      } else {
        pb.push_back(i);
        know = true;
        continue;
      }
    }
    if (Ask({i}, {pa.back()})) {
      pa.push_back(i);
      know = false;
      continue;
    }
    if (Ask({i}, {pb.back()})) {
      pb.push_back(i);
      know = true;
      continue;
    }
    while (!pb.empty()) {
      pa.push_back(pb.back());
      pb.pop_back();
    }
    pb.push_back(i);
    know = false;
  }
  if (pa.empty()) {
    return pb;
  }
  if (pb.empty()) {
    return pa;  
  }
  if (!Ask(pa, pb)) {
    if ((int) pa.size() < (int) pb.size()) {
      swap(pa, pb);
    }
    return pa;
  }
  vector<int> L, R;
  L.push_back(pa[0]);
  if ((int) pa.size() > 1) {
    L.push_back(pa.back());
  }
  R.push_back(pb[0]);
  if ((int) pb.size() > 1) {
    R.push_back(pb.back());
  }
  if (Ask(L, R)) {
    if (Ask({pa[0]}, {pb[0]})) {
      reverse(pa.begin(), pa.end());
      vector<int> res;
      for (int i : pa) {
        res.push_back(i);
      }
      for (int i : pb) {
        res.push_back(i);
      }
      return res;
    }
    if (Ask({pa.back()}, {pb[0]})) {
      vector<int> res;
      for (int i : pa) {
        res.push_back(i);
      }
      for (int i : pb) {
        res.push_back(i);
      }
      return res;
    }
    if (Ask({pa[0]}, {pb.back()})) {
      vector<int> res;
      for (int i : pb) {
        res.push_back(i);
      }
      for (int i : pa) {
        res.push_back(i);
      }
      return res;
    }
    reverse(pa.begin(), pa.end());
    vector<int> res;
    for (int i : pb) {
      res.push_back(i);
    }
    for (int i : pa) {
      res.push_back(i);
    }
    return res;
  }
  int x = -1, y = -1;
  {
    int low = 0, high = (int) pa.size() - 1;
    while (low <= high) {
      int mid = (low + high) >> 1;
      vector<int> qv;
      for (int i = 0; i <= mid; i++) {
        qv.push_back(pa[i]);
      }
      if (Ask(qv, pb)) {
        x = mid;
        high = mid - 1;
      } else {
        low = mid + 1;
      }
    }
  }
  {
    int low = 0, high = (int) pb.size() - 1;
    while (low <= high) {
      int mid = (low + high) >> 1;
      vector<int> qv;
      for (int i = 0; i <= mid; i++) {
        qv.push_back(pb[i]);
      }
      if (Ask({pa[x]}, qv)) {
        y = mid;
        high = mid - 1;
      } else {
        low = mid + 1;
      }
    }
  }
  int ca = (int) pa.size();
  int cb = (int) pb.size();
  vector<int> new_a;
  for (int i = 0; i < ca; i++) {
    new_a.push_back(pa[(i + 1 + x) % ca]);
  }
  pa = new_a;
  vector<int> new_b;
  for (int i = 0; i < cb; i++) {
    new_b.push_back(pb[(i + 1 + y) % cb]);
  }
  pb = new_b;
  reverse(pb.begin(), pb.end());
  vector<int> res;
  for (int i : pa) {
    res.push_back(i);
  }
  for (int i : pb) {
    res.push_back(i);
  }
  return res;
}

• Subtask 0: 0 / 0
• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 25 / 25
• Subtask 4: 60 / 60