Submission #1042477

#	Time	Username	Problem	Language	Result	Execution time	Memory
1042477		yanb	Thousands Islands (IOI22_islands)	C++17	10.85 / 100	31 ms	6284 KiB

islands

#include <bits/stdc++.h>
	
using namespace std;
	
//#define int long long
//#define pii pair<long long, long long>
	
union Ans {
	bool b;
	vector<int> v;
	Ans(bool b) : b(b) {}
	Ans(vector<int> v) : v(v) {}
	~Ans() {}
	Ans(const Ans&) {}
};
	
Ans n2(int n, int M, vector<int> U, vector<int> V) {
	vector<int> u0, u1;
	for (int i = 0; i < M; i++) {
		if (U[i]) u1.push_back(i);
		else u0.push_back(i);
	}
	
	if (u1.size() > 0 && u0.size() > 1) {
		vector<int> ans = {u0[0], u1[0], u0[1], u0[0], u1[0], u0[1]};
		return ans;
	} else {
		return false;
	}
}
	
void dfs(int v, vector<vector<int>> &g, vector<bool> &uu) {
	if (uu[v]) return;
	uu[v] = 1;
	for (int u : g[v]) {
		dfs(u, g, uu);
	}
}
	
Ans undirected(int n, int M, vector<int> U, vector<int> V) {
	vector<vector<int>> g(n);
	for (int i = 0; i < M; i++) {
		g[U[i]].push_back(V[i]);
	}
	
	if (g[0].size() > 1) return true;
	
	vector<bool> uu(n);
	dfs(0, g, uu);
	for (int i = 0; i < n; i++) {
		if (g[i].size() > 2 && uu[i]) return true;
	}
	
	return false;
}
	
Ans find_journey(int n, int M, vector<int> U, vector<int> V) {
	if (n == 2) return n2(n, M, U, V);
	return undirected(n, M, U, V);
}
	
#ifdef ONLINE_JUDGE
signed main() {
	Ans ans = find_journey(3, 4, {0, 1, 1, 0}, {1, 0, 0, 1});
	if (ans.b) {
		for (int x : ans.v) cout << x << " ";
		cout << "\n";
	}
}
#endif

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