Submission #1009269

#	Time	Username	Problem	Language	Result	Execution time	Memory
1009269		CSQ31	Thousands Islands (IOI22_islands)	C++17	11.90 / 100	36 ms	35464 KiB

islands

#include "islands.h"
#include<bits/stdc++.h>
#include <variant>
#include <vector>
using namespace std;
#define sz(a) (int)(a.size())
#define pb push_back
#define fi first
#define se second
typedef pair<int,int> pii;
const int MAXN = 5e5+5;
bool dead[MAXN],mark[MAXN];
int outdeg[MAXN];
vector<pii>g[MAXN],gr[MAXN];
void upd(int v){
	while(!g[v].empty() && dead[g[v].back().se])g[v].pop_back();
}
variant<bool, vector<int>> find_journey(int N, int M, vector<int> U, vector<int> V){
	for(int i=0;i<M;i++){
		gr[V[i]].pb({U[i],i});
		g[U[i]].pb({V[i],i});
		outdeg[U[i]]++;
	}
	vector<int>del;
	for(int i=0;i<N;i++){
		//cout<<i<<" "<<sz(g[i])<<'\n';
		if(g[i].empty()){
			del.pb(i);
			mark[i] = 1;
		}
	}
	int cur = 0;
	while(true){
		if(mark[cur])return false;
		while(!del.empty()){
			vector<int>tmp;
			for(int u:del){
				for(pii x:gr[u]){
					int v = x.fi;
					outdeg[v]--;
					dead[x.se] = 1;
					if(!outdeg[v]){
						tmp.pb(v);
						mark[v] = 1;
					}
				}
			}
			del = tmp;
		}
		if(mark[cur])return false;

		upd(cur);
		if(outdeg[cur] > 1)return true;
		else if(outdeg[cur] == 0)return false;
		else{
			del.push_back(cur);
			mark[cur] = 1;
			upd(cur);
			cur = g[cur].back().fi;
		}
	}

}

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