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Submission #823663

# Submission time Handle Problem Language Result Execution time Memory
823663 2023-08-12T23:50:02 Z NK_ One-Way Streets (CEOI17_oneway) C++17
100 / 100
 67 ms 14704 KB 
// Success consists of going from failure to failure without loss of enthusiasm
#include <bits/stdc++.h>

using namespace std;

#define nl '\n'
#define pb push_back
#define mp make_pair
#define f first
#define s second
#define sz(x) int(x.size())

template<class T> using V = vector<T>;
using vi = V<int>;
using pi = pair<int, int>;

struct DSU {
	vi e; void init(int N) { e = vi(N, -1); }
	int get(int x) { return e[x] < 0 ? x : e[x] = get(e[x]); }
	bool unite(int x, int y) {
		x = get(x), y = get(y); if (x == y) return 0;
		e[x] += e[y]; e[y] = x; return 1;
	}
};
int main() {
	cin.tie(0)->sync_with_stdio(0);
	
	int N, M; cin >> N >> M;

	DSU D; D.init(N);
	V<V<pi>> adj(N); V<pi> ex, E;
	string ans(M, 'B');
	for(int i = 0; i < M; i++) {
		int u, v; cin >> u >> v; --u, --v;
		E.pb(mp(u, v));
		if (D.unite(u, v)) adj[u].pb(mp(v, i)), adj[v].pb(mp(u, i));
		else ex.pb(mp(u, v));
	}

	V<pi> par(N); vi dep(N, -1);
	function<void(int)> dfs = [&](int u) {
		for(auto& v : adj[u]) if (v.f != par[u].f) { 
			par[v.f] = mp(u, v.s); dep[v.f] = dep[u] + 1; dfs(v.f); 
		}
	};
	
	for(int r = 0; r < N; r++) if (dep[r] == -1) {
		par[r] = mp(-1, -1); dep[r] = 0; dfs(r);
	}


	D.init(N);
	for(const auto& p : ex) {
		int u, v; tie(u, v) = p;

		while(1) {
			int a = D.get(u), b = D.get(v);
			if (a == b) break;
			if (dep[a] < dep[b]) swap(a, b);
			assert(par[a].f != -1); D.unite(par[a].f, a);
		}
	}

	vi to(M, -1);
	int Q; cin >> Q;
	for(int i = 0; i < Q; i++) {
		int u, v; cin >> u >> v; --u, --v;
		if (D.get(u) == D.get(v)) continue;

		while(1) {
			int a = D.get(u), b = D.get(v);
			if (a == b) break;
			if (dep[a] < dep[b]) swap(a, b);
			to[par[a].s] = (D.get(u) == a ? par[a].f : a);
			assert(par[a].f != -1); D.unite(par[a].f, a);
		}
	}

	for(int i = 0; i < M; i++) if (to[i] != -1) {
		ans[i] = (E[i].f == to[i] ? 'L' : 'R');
	}

	cout << ans << nl;

    return 0;
}

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 1 ms 340 KB Output is correct
7 Correct 1 ms 340 KB Output is correct
8 Correct 1 ms 340 KB Output is correct
9 Correct 1 ms 340 KB Output is correct
10 Correct 1 ms 340 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 1 ms 340 KB Output is correct
7 Correct 1 ms 340 KB Output is correct
8 Correct 1 ms 340 KB Output is correct
9 Correct 1 ms 340 KB Output is correct
10 Correct 1 ms 340 KB Output is correct
11 Correct 30 ms 3804 KB Output is correct
12 Correct 25 ms 4624 KB Output is correct
13 Correct 28 ms 5816 KB Output is correct
14 Correct 33 ms 7640 KB Output is correct
15 Correct 46 ms 8356 KB Output is correct
16 Correct 37 ms 9284 KB Output is correct
17 Correct 51 ms 11112 KB Output is correct
18 Correct 65 ms 9252 KB Output is correct
19 Correct 34 ms 12532 KB Output is correct
20 Correct 32 ms 5840 KB Output is correct
21 Correct 26 ms 6152 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 1 ms 340 KB Output is correct
7 Correct 1 ms 340 KB Output is correct
8 Correct 1 ms 340 KB Output is correct
9 Correct 1 ms 340 KB Output is correct
10 Correct 1 ms 340 KB Output is correct
11 Correct 30 ms 3804 KB Output is correct
12 Correct 25 ms 4624 KB Output is correct
13 Correct 28 ms 5816 KB Output is correct
14 Correct 33 ms 7640 KB Output is correct
15 Correct 46 ms 8356 KB Output is correct
16 Correct 37 ms 9284 KB Output is correct
17 Correct 51 ms 11112 KB Output is correct
18 Correct 65 ms 9252 KB Output is correct
19 Correct 34 ms 12532 KB Output is correct
20 Correct 32 ms 5840 KB Output is correct
21 Correct 26 ms 6152 KB Output is correct
22 Correct 50 ms 11124 KB Output is correct
23 Correct 59 ms 9204 KB Output is correct
24 Correct 54 ms 9256 KB Output is correct
25 Correct 67 ms 14704 KB Output is correct
26 Correct 47 ms 10632 KB Output is correct
27 Correct 49 ms 9320 KB Output is correct
28 Correct 20 ms 2408 KB Output is correct
29 Correct 38 ms 5804 KB Output is correct
30 Correct 36 ms 5912 KB Output is correct
31 Correct 37 ms 5824 KB Output is correct
32 Correct 40 ms 10176 KB Output is correct