Submission #1149636

#	Time	Username	Problem	Language	Result	Execution time	Memory
1149636		byunjaewoo	Thousands Islands (IOI22_islands)	C++20	8.40 / 100	21 ms	4932 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<pair<int, int>> adj[1010];
  bool chk[1010], chk2[1010];
  int prv[1010], pw[1010];
  fill(chk, chk+N, false), fill(chk2, chk2+N, false);
  fill(prv, prv+N, -1), fill(pw, pw+N, -1);
  prv[0]=0;
  for(int i=0; i<M; i+=2) adj[U[i]].push_back({V[i], i});
  vector<int> ret;
  function<void(int)> dfs=[&](int curr) {
    chk[curr]=true, chk2[curr]=true;
    for(auto [next, k]:adj[curr]) {
      if(!chk[next]) prv[next]=curr, pw[next]=k, dfs(next);
      else if(chk2[next]) {
        ret.push_back(k+1);
        for(int i=curr; i!=next; i=prv[i]) ret.push_back(pw[i]+1);
        ret.push_back(k);
        for(int i=curr; i!=next; i=prv[i]) ret.push_back(pw[i]);
        vector<int> tmp;
        tmp.push_back(k);
        for(int i=curr; i!=next; i=prv[i]) tmp.push_back(pw[i]);
        tmp.push_back(k+1);
        for(int i=curr; i!=next; i=prv[i]) tmp.push_back(pw[i]+1);
        reverse(tmp.begin(), tmp.end());
        for(int i:tmp) ret.push_back(i);
        for(int i=next; i; i=prv[i]) ret.push_back(pw[i]);
        reverse(ret.begin(), ret.end());
        for(int i=next; i; i=prv[i]) ret.push_back(pw[i]);
      }
      if(!ret.empty()) return;
    }
    chk2[curr]=false;
  };
  dfs(0);
  if(ret.empty()) return false;
  return ret;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 5
• Subtask 3: 0 / 21
• Subtask 4: 8.4 / 24
• Subtask 5: 0 / 45