Submission #812721

#	Time	Username	Problem	Language	Result	Execution time	Memory
812721		blackyuki	Thousands Islands (IOI22_islands)	C++17	1.75 / 100	41 ms	12744 KiB

islands

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> P;
typedef vector<ll> vi;
typedef vector<vi> vvi;
typedef vector<P> vp;
typedef vector<vp> vvp;
typedef vector<bool> vb;
#define rep(i,n) for(ll i=0;i<(ll)(n);i++)
#define REP(i,k,n) for(ll i=(ll)(k);i<(ll)(n);i++)
#define all(a) a.begin(),a.end()
#define fi first
#define se second
#define pb emplace_back
#define lb(v,k) (lower_bound(all(v),k)-v.begin())
template<class T> bool chmin(T&a,T b){if(a>b){a=b;return true;}return false;}
template<class T> bool chmax(T&a,T b){if(a<b){a=b;return true;}return false;}
template<class T> void out(T a){cout<<a<<'\n';}
template<class T> void outv(T v){rep(i,v.size()){if(i)cout<<' ';cout<<v[i];}cout<<'\n';}
const ll inf=1001001001001;

#include "islands.h"

std::variant<bool, std::vector<int>> find_journey(int N, int M, std::vector<int> U, std::vector<int> V) {
  vvp g(N),rg(N);
  rep(i,M){
    g[U[i]].pb(V[i],i);
    rg[V[i]].pb(U[i],i);
  }
  vi cnt(N);rep(i,N)cnt[i]=g[i].size();
  vb dead(N,false);
  queue<ll> que;
  auto f=[&](ll i){
    que.push(i);
    while(!que.empty()){
      ll t=que.front();que.pop();
      for(auto x:rg[t])if(!dead[x.fi]){
        cnt[x.fi]--;
        if(cnt[x.fi]==0){
          dead[x.fi]=true;que.push(x.fi);
        }
      }
    }
  };
  rep(i,N)if(!dead[i]&&cnt[i]==0){
    dead[i]=true;f(i);
  }
  if(dead[0])return false;
  ll cur=0;
  while(true){
    dead[cur]=true;f(cur);
    vi nex;
    for(auto x:g[cur])if(!dead[x.fi])nex.pb(x.fi);
    if(nex.size()==0)return false;
    if(nex.size()>1)return true;
    cur=nex[0];
  }
}

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