Submission #628183

#	Time	Username	Problem	Language	Result	Execution time	Memory
628183		Turkhuu	Thousands Islands (IOI22_islands)	C++17	8.40 / 100	212 ms	16304 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 (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 < s; i++) {
          for (int j = 0; j < s; j++) {
            ans.push_back(c[(s - i + j) % s]);
          }
          for (int j = 0; j < s; j++) {
            ans.push_back(c[(s - i + j) % s] ^ 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:40:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   40 |         for (int i = 0; i < a.size(); i++) {
      |                         ~~^~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 5
• Subtask 3: 0 / 21
• Subtask 4: 8.399999999999999 / 24
• Subtask 5: 0 / 45