Submission #832889

#	Time	Username	Problem	Language	Result	Execution time	Memory
832889		Username4132	Thousands Islands (IOI22_islands)	C++17	17.50 / 100	1087 ms	8696 KiB

islands

#include "islands.h"

#include <variant>
#include<iostream>
#include <vector>
using namespace std;
using pii = pair<int, int>;
#define forn(i, n) for(int i=0; i<(int)n; ++i)
#define PB push_back

const int MAXN = 100010;
int n, m;
bool marked[MAXN], inst[MAXN], vis[MAXN];
vector<int> g[MAXN];
vector<int> st;

bool dfs1(int v){
  vis[v]=inst[v]=true;
  st.PB(v);
  bool ret=false;
  for(int to:g[v]) if(!marked[to] && !vis[to]){
    ret|=dfs1(to);
  }
  else if(inst[to]){
    ret=true;
  }
  st.pop_back();
  inst[v]=false;
  return ret;
}


variant<bool, vector<int>> find_journey(int N, int M, vector<int> U, vector<int> V) {
  n=N, m=M;
  forn(i, m) g[U[i]].PB(V[i]);
  int cur=0;
  while(true){
    vector<int> nxt;
    for(int to:g[cur]) if(!marked[to]){
      if(dfs1(to)) nxt.PB(to);
      forn(i, n) vis[i]=false;
    }
    if(nxt.empty()) return false;
    if((int)nxt.size() > 1){
      vector<int> emp;
      return emp;
    }
    marked[cur]=true;
    cur=nxt.back();
  }
}

• Subtask 1: 0 / 5
• Subtask 2: 1.75 / 5
• Subtask 3: 7.35 / 21
• Subtask 4: 8.399999999999999 / 24
• Subtask 5: 0 / 45