Submission #1038496

#	Time	Username	Problem	Language	Result	Execution time	Memory
1038496		erray	Longest Trip (IOI23_longesttrip)	C++17	100 / 100	16 ms	856 KiB

longesttrip

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

using namespace std;

#ifdef DEBUG 
  #include "/home/ioi/egoi2024/d2/debug.h"
#else 
  #define debug(...) void(37)
#endif

vector<int> m(vector<int> x, vector<int> y) {
  vector<int> res;
  res = x;
  res.insert(res.end(), y.begin(), y.end());
  return res;
}

std::vector<int> longest_trip(int N, int D) {
  array<vector<int>, 2> l;
  l[0] = {0}; l[1] = {1};
  bool dis = false;
  for (int i = 2; i < N; ++i) {
    if (are_connected({i}, {l[0].back()})) {
      l[0].push_back(i);
      dis = false;
    } else if (dis) {
      l[1].push_back(i);
      dis = false;
    } else if (are_connected({i}, {l[1].back()})) {
      l[1].push_back(i);
      dis = true;
    } else {
      dis = int(l[1].size()) == 1;
      l[0] = m(l[0], vector<int>(l[1].rbegin(), l[1].rend()));
      l[1] = {i};
    }
  } 
  debug(l);
  if (!are_connected(l[0], l[1])) {
    return  int(l[0].size()) > int(l[1].size()) ? l[0] : l[1];
  }
  vector<int> fe0, fe1;
  int l0 = int(l[0].size());
  int l1 = int(l[1].size());
  for (int i = 0; i < l0; ++i) {
    if (i == 0 || i == l0 - 1) fe0.push_back(l[0][i]);
  }
  for (int i = 0; i < l1; ++i) {
    if (i == 0 || i == l1 - 1) fe1.push_back(l[1][i]);
  }
  if (!are_connected(fe0, fe1)) {
    int s = -1;
    {
      int low = 0, high = int(l[1].size()) - 1;
      while (low < high) {
        int mid = (low + high) >> 1;
        if (are_connected(l[0], vector<int>(l[1].begin(), l[1].begin() + mid + 1))) {
          high = mid;
        } else {
          low = mid + 1;
        }
      }
      s = low;
    }
    int f = -1;
    {
      int low = 0, high = int(l[0].size()) - 1;
      while (low < high) {
        int mid = (low + high) >> 1;
        if (are_connected({l[1][s]}, vector<int>(l[0].begin(), l[0].begin() + mid + 1))) {
          high = mid;
        } else {
          low = mid + 1;
        }
      }
      f = low;
    }
    rotate(l[1].begin(), l[1].begin() + s, l[1].end());
    if (f != int(l[0].size()) - 1) rotate(l[0].begin(), l[0].begin() + f + 1, l[0].end());
    vector<int> ans = m(l[0], l[1]);
    return ans;
  }
  vector<int> ans;
  for (int it = 0; it < 2; ++it) {
    for (int it1 = 0; it1 < 2; it1++) {
      if (are_connected({l[0].back()}, {l[1][0]})) {
        ans = m(l[0], l[1]);
      }
      reverse(l[1].begin(), l[1].end());
    }
    reverse(l[0].begin(), l[0].end());
  }
  return ans;
}

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