Submission #841611

#	Time	Username	Problem	Language	Result	Execution time	Memory
841611		flashmt	Longest Trip (IOI23_longesttrip)	C++17	85 / 100	12 ms	852 KiB

longesttrip

#include "longesttrip.h"
#include <bits/stdc++.h>
using namespace std;

vector<int> longest_trip(int n, int d)
{
  vector<int> c[2];
  c[0] = {0};
  for (int i = 1; i < n; i++)
  {
    int x = c[0].back();
    if (are_connected({i}, {x})) c[0].push_back(i);
    else if (empty(c[1])) c[1].push_back(i);
    else
    {
      int y = c[1].back();
      if (are_connected({i}, {y})) c[1].push_back(i);
      else
      {
        while (!empty(c[1]))
        {
          c[0].push_back(c[1].back());
          c[1].pop_back();
        }
        c[1].push_back(i);
      }
    }
  }

  if (size(c[1]) > size(c[0]))
    swap(c[0], c[1]);

  if (empty(c[1]))
    return c[0];

  if (!are_connected(c[0], c[1]))
    return c[0];

  for (int u : {0, 1})
  {
    int v = u ^ 1;
    int x = c[v][0];

    if (are_connected({x}, {c[u][0]}))
    {
      reverse(begin(c[u]), end(c[u]));
      for (int y : c[v])
        c[u].push_back(y);
      return c[u];
    }

    if (are_connected({x}, {c[u].back()}))
    {
      for (int y : c[v])
        c[u].push_back(y);
      return c[u];
    }
  }

  // both c[0] and c[1] are cycles
  int low = 0, high = size(c[0]);
  while (high - low > 1)
  {
    int mid = (low + high) / 2;
    if (are_connected(vector<int>(begin(c[0]) + low, begin(c[0]) + mid), c[1])) high = mid;
    else low = mid;
  }
  int id0 = low;

  low = 0, high = size(c[1]);
  while (high - low > 1)
  {
    int mid = (low + high) / 2;
    if (are_connected(vector<int>(begin(c[1]) + low, begin(c[1]) + mid), {c[0][id0]})) high = mid;
    else low = mid;
  }
  int id1 = low;

  if (id0 < size(c[0]) - 1)
    rotate(begin(c[0]), begin(c[0]) + (id0 + 1), end(c[0]));
  rotate(begin(c[1]), begin(c[1]) + id1, end(c[1]));
  for (int i : c[1])
    c[0].push_back(i);
  return c[0];
}

Compilation message (stderr)

longesttrip.cpp: In function 'std::vector<int> longest_trip(int, int)':
longesttrip.cpp:79:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   79 |   if (id0 < size(c[0]) - 1)
      |       ~~~~^~~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 25 / 25
• Subtask 4: 45 / 60