Submission #1150027

#	TimeUTC-0	Username	Problem	Language	Result	Execution time	Memory
1150027	2025-02-13 15:58:07	byunjaewoo	Thousands Islands (IOI22_islands)	C++20	100 / 100	130 ms	32836 KiB

islands

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#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<multiset<pair<int, int>>> tadj(N);
  vector<set<array<int, 3>>> adj(N);
  vector<vector<pair<int, int>>> radj(N);
  vector<int> ret, st;
  for(int i=0; i<M; i++) tadj[U[i]].insert({V[i], i}), radj[V[i]].push_back({U[i], i});
  queue<int> q;
  auto del=[&]() {
    while(!q.empty()) {
      int curr=q.front(); q.pop();
      for(auto [next, k]:radj[curr]) {
        tadj[next].erase(tadj[next].find({curr, k}));
        if(tadj[next].empty()) q.push(next);
      }
      radj[curr].clear();
    }
  };
  int p=0;
  for(int i=0; i<N; i++) if(tadj[i].empty()) q.push(i);
  del();
  if(tadj[0].empty()) return false;
  while(tadj[p].size()==1) {
    q.push(p), del();
    if(tadj[p].empty()) return false;
    st.push_back(tadj[p].begin()->second);
    p=tadj[p].begin()->first;
 
 
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• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 21 / 21
• Subtask 4: 24 / 24
• Subtask 5: 45 / 45