Submission #628196

#	Time	Username	Problem	Language	Result	Execution time	Memory
628196		Turkhuu	Thousands Islands (IOI22_islands)	C++17	25.75 / 100	40 ms	6100 KiB

islands

#include "islands.h"
#include <bits/stdc++.h>
using namespace std;
variant<bool, vector<int>> find_journey(int N, int M, vector<int> U, vector<int> V) {
  vector<vector<pair<int, int>>> G(N);
  for (int i = 0; i < M; i++) {
    G[U[i]].emplace_back(V[i], i);
  }
  vector<int> E(N, -1), ans, R(N);
  function<bool(int)> dfs = [&](int A) {
    R[A] = 1;
    for (auto [B, C] : G[A]) {
      if (E[A] != (C ^ 1)) {
        if (R[B] == 1) {
          vector<int> a;
          int F = B;
          while (F != 0) {
            a.push_back(E[F]);
            F = U[E[F]];
          }
          vector<int> c;
          int D = A;
          while (D != B) {
            c.push_back(E[D]);
            D = U[E[D]];
          }
          reverse(c.begin(), c.end());
          c.push_back(C);
          int s = c.size();
          for (int i = a.size() - 1; i >= 0; i--) {
            ans.push_back(a[i]);
          }
          for (int i = 0; i < c.size(); i++) {
            ans.push_back(c[i]);
          }
          ans.push_back(c[0] ^ 1);
          ans.push_back(c[0]);
          for (int i = c.size() - 1; i > 0; i--) {
            ans.push_back(c[i]);
          }
          ans.push_back(c[0] ^ 1);
          for (int i = 0; i < a.size(); i++) {
            ans.push_back(a[i]);
          }
          return true;
        }
        if (R[B] == 0) {
          E[B] = C;
          if (dfs(B)) {
            return true;
          }
        }
      }
    }
    R[A] = 2;
    return false;
  };
  E[0] = -2;
  if (dfs(0)) {
    return ans;
  } else {
    return false;
  }
}

Compilation message (stderr)

islands.cpp: In lambda function:
islands.cpp:33:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   33 |           for (int i = 0; i < c.size(); i++) {
      |                           ~~^~~~~~~~~~
islands.cpp:42:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   42 |           for (int i = 0; i < a.size(); i++) {
      |                           ~~^~~~~~~~~~
islands.cpp:29:15: warning: unused variable 's' [-Wunused-variable]
   29 |           int s = c.size();
      |               ^

• Subtask 1: 0 / 5
• Subtask 2: 1.75 / 5
• Subtask 3: 0 / 21
• Subtask 4: 24 / 24
• Subtask 5: 0 / 45