Submission #825724

#	Time	Username	Problem	Language	Result	Execution time	Memory
825724		top34051	Thousands Islands (IOI22_islands)	C++17	10 / 100	23 ms	4356 KiB

islands

#include "islands.h"

#include <variant>
#include <vector>

std::variant<bool, std::vector<int>> find_journey(int N, int M,
                                                  std::vector<int> U,
                                                  std::vector<int> V) {
  // Subtask 1
  if (N == 2) {
    std::vector<int> way, yaw;
    for (int i = 0; i < M; ++i) {
      int u = U[i], v = V[i];
      if (u == 0) {
        way.push_back(i);
      } else {
        yaw.push_back(i);
      }
    }
    if ((int)way.size() >= 2 && (int)yaw.size() >= 1) {
      return std::vector({way[0], yaw[0], way[1], way[0], yaw[0], way[1]});
    }
  }
  // Subtask 2
  if (N >= 2) {
    std::vector<std::vector<int>> id(3, std::vector<int>(3, -1));
    for (int i = 0; i < M; ++i) {
      int u = U[i], v = V[i];
      if (u * v == 0 && u <= 2 && v <= 2) {
        id[u][v] = i;
      }
    }
    if (id[0][1] != -1 && id[1][0] != -1 && id[0][2] != -1 && id[2][0] != -1) {
      return std::vector({id[0][1], id[1][0], id[0][2], id[2][0], id[1][0],
                          id[0][1], id[2][0], id[0][2]});
    }
  }
  return false;
}

Compilation message (stderr)

islands.cpp: In function 'std::variant<bool, std::vector<int, std::allocator<int> > > find_journey(int, int, std::vector<int>, std::vector<int>)':
islands.cpp:13:21: warning: unused variable 'v' [-Wunused-variable]
   13 |       int u = U[i], v = V[i];
      |                     ^

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 0 / 21
• Subtask 4: 0 / 24
• Subtask 5: 0 / 45