Submission #894390

#	Time	Username	Problem	Language	Result	Execution time	Memory
894390		Trisanu_Das	Keys (IOI21_keys)	C++17	100 / 100	579 ms	60104 KiB

keys

#include <bits/stdc++.h>
using namespace std;
struct dsu {
	int n;
	vector<int> p;
	dsu(int _n): n(_n), p(_n) {
		iota(begin(p), end(p), 0);
	}
	int leader(int x) {
		return p[x] == x ? x : p[x] = leader(p[x]);
	}
};
vector<int> find_reachable(vector<int> r, vector<int> U, vector<int> V, vector<int> C) {
	const auto n = int(r.size()), m = int(U.size());
	vector<vector<pair<int, int>>> e(n);
	for (int i = 0; i < m; ++i) {
		e[U[i]].emplace_back(V[i], C[i]);
		e[V[i]].emplace_back(U[i], C[i]);
	}
	dsu d(n);
	auto num = numeric_limits<size_t>::max();
	vector<int> ans, solved(n);
	while (true) {
		vector nodes(n, vector<int>());
		vector<int> vis(n), changed, appear(n), res;
		auto BFS = [&] (int S) {
			for (int x: res)
				appear[r[x]] = 0;
			for (int x: changed)
				nodes[x].clear();
			res.clear(), changed.clear();
			queue<int> Q;
			Q.push(S);
			while (!empty(Q)) {
				const auto u = Q.front();
				Q.pop();
				if (S != d.leader(u)) {
					vis[d.leader(u)] = 1;
					d.p[S] = d.leader(u);
					return;
				}
				if (vis[u]) continue;
				vis[u] = 1, res.push_back(u);
				if (!appear[r[u]]) {
					appear[r[u]] = 1;
					for (int v: nodes[r[u]]) Q.push(v);
				}
				for (auto [v, c]: e[u])
					if (appear[c]) Q.push(v);
					else nodes[c].push_back(v), changed.push_back(c);
			}
			solved[S] = 1;
			if (size(res) < num) num = size(ans = res);
			else if (size(res) == num)
				for (int x: res) ans.push_back(x);
		};
		bool hav = 0;
		for (int i = 0; i < n; ++i)
			if (d.leader(i) == i && !vis[i] && !solved[i])
				hav = 1, BFS(i);
		if (!hav) break;
	}
	vector<int> ret(n);
	for (int x: ans) ret[x] = 1;
	return ret;
}

• Subtask 1: 9 / 9
• Subtask 2: 11 / 11
• Subtask 3: 17 / 17
• Subtask 4: 30 / 30
• Subtask 5: 33 / 33