제출 #1042533

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1042533		yanb	수천개의 섬 (IOI22_islands)	C++17	6.75 / 100	37 ms	32340 KiB

islands

#include <bits/stdc++.h>
	
using namespace std;
	
//#define int long long
#define pii pair<int, int>
	
variant<bool, vector<int>> 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, int p, vector<vector<pii>> &g, vector<bool> &uu, vector<int> &ps) {
	if (uu[v]) return;
	uu[v] = 1;
	ps[v] = p;
	for (auto [u, _] : g[v]) {
		dfs(u, v, g, uu, ps);
	}
}
	
variant<bool, vector<int>> undirected(int n, int M, vector<int> U, vector<int> V) {
	vector<vector<pii>> g(n);
	vector<vector<vector<int>>> gh(n, vector<vector<int>>(n));
	for (int i = 0; i < M; i++) {
		g[U[i]].push_back({V[i], i});
		gh[U[i]][V[i]].push_back(i);
	}
	
	if (g[0].size() > 1) {
		int u = g[0][0].first, v = g[0][1].first;
		if (u == v) {
			vector<int> ans = {g[0][0].second, g[u][0].second, g[0][1].second, 
				g[0][0].second, g[u][0].second, g[0][1].second};
			return true;
		}
		vector<int> ans = {g[0][0].second, g[u][0].second, g[0][1].second, g[v][0].second,
			g[u][0].second, g[0][0].second, g[v][0].second, g[0][1].second};
		return true;
	}
	
	vector<bool> uu(n);
	vector<int> p(n);
	dfs(0, 0, g, uu, p);
	for (int i = 0; i < n; i++) {
		if (g[i].size() > 2 && uu[i]) {
			vector<int> ans, path;
			int v = i;
			while (v != 0) {
				path.push_back(v);
				v = p[v];
			}
			path.push_back(0);
			
			reverse(path.begin(), path.end());
			for (int i = 0; i < (int) path.size() - 1; i++) {
				ans.push_back(gh[path[i]][path[i + 1]][0]);
			}
			reverse(path.begin(), path.end());

			vector<int> xy;
			for (auto [u, _] : g[i]) {
				if (u != path[1]) xy.push_back(u);
			}
			int x = xy[0], y = xy[1];
			
			if (x == y) {
				ans.push_back(gh[i][x][0]);
				ans.push_back(gh[x][i][0]);
				ans.push_back(gh[i][x][1]);
				ans.push_back(gh[i][x][0]);
				ans.push_back(gh[x][i][0]);
				ans.push_back(gh[i][x][1]);
			} else {
				ans.push_back(gh[i][x][0]);
				ans.push_back(gh[x][i][0]);
				ans.push_back(gh[i][y][0]);
				ans.push_back(gh[y][i][0]);
				ans.push_back(gh[x][i][0]);
				ans.push_back(gh[i][x][0]);
				ans.push_back(gh[y][i][0]);
				ans.push_back(gh[i][y][0]);
			}

			for (int i = 0; i < (int) path.size() - 1; i++) {
				ans.push_back(gh[path[i + 1]][path[i]][0]);
			}

			return ans;
		}
	}
	
	return false;
}
	
variant<bool, vector<int>> 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() {
	variant<bool, vector<int>> ans = find_journey(5, 8, {0, 1, 1, 1, 2, 3, 4, 4}, 
		{4, 4, 2, 3, 1, 1, 1, 0});
	for (int x : get<vector<int>>(ans)) cout << x << " ";
	cout << "\n";
}
#endif

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