Submission #1139486

#	Time	Username	Problem	Language	Result	Execution time	Memory
1139486		Saul0906	Thousands Islands (IOI22_islands)	C++20	10.85 / 100	28 ms	16888 KiB

islands

#include "islands.h"
#include <bits/stdc++.h>
#define rep(a,b,c) for(ll a=b; a<c; a++)
#define repr(a,b,c) for(ll a=b-1; a>c-1; a--)
#define repa(a,b) for(auto a:b)
#define ll long long
#define pll pair<ll, ll>
#define pii pair<int, int>
#define fi first
#define se second
#define pb push_back
#define mid ((l+r)>>1)
#define ppb pop_back
#define pf push_front
#define all(a) a.begin(),a.end()

using namespace std;
using vi = vector<int>;
template<typename T>
using vec = vector<T>;

const int N=2e5+5;

vec<pii> adj[N], iadj[N];
bool rem[N], vis[N];
int out[N];

bool solve(int u, int p){
	int c=0;
	repa(v,adj[u]){
		if(rem[v.se] || v.fi==p) continue;
		c++;
	}
	if(out[u]>2 || c>=2) return true;
	vis[u]=true;
	repa(v,adj[u]){
		if(rem[v.se] || vis[v.fi]) continue;
		if(solve(v.fi,u)) return true;
	}
	return false;
}

std::variant<bool, std::vector<int>> find_journey(
	int N, int M, std::vector<int> U, std::vector<int> V){
	rep(i,0,M) adj[U[i]].pb({V[i],i});
	rep(i,0,M) iadj[V[i]].pb({U[i],i}), out[U[i]]++;
	int u;
	queue<int> nodes, edges;
	rep(i,0,N) if(!out[i]) nodes.push(i);
	do{
		while(nodes.size()){
			u=nodes.front();
			nodes.pop();
			repa(e,iadj[u]) edges.push(e.se);
		}
		while(edges.size()){
			u=edges.front();
			edges.pop();
			rem[u]=true;
			out[U[u]]--;
			if(!out[U[u]]) nodes.push(u);
		}
	}while(nodes.size());
	return solve(0,-1);
}

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