oj.uz

Submission #572511

# Submission time Handle Problem Language Result Execution time Memory
572511 2022-06-04T14:49:17 Z _karan_gandhi One-Way Streets (CEOI17_oneway) C++17
100 / 100
 70 ms 17460 KB 
#include <bits/stdc++.h>
using namespace std;

#define all(v) v.begin(), v.end()
#define endl '\n'
#define pl(var) " [" << #var << ": " << (var) << "] "
#define ll long long

template<typename A, typename B> ostream& operator<<(ostream &cout, pair<A, B> const &p) { return cout << "[" << p.first << ", " << p.second << "]"; }
template<typename A> ostream& operator<<(ostream &cout, vector<A> const &v) { cout << "["; for(int i = 0; i < (int)v.size(); i++) {if (i) cout << ", "; cout << v[i];} return cout << "]";}
template<typename A, typename B> istream& operator>>(istream& cin, pair<A, B> &p) { cin >> p.first; return cin >> p.second; }

vector<vector<pair<int, int>>> adj;
vector<pair<int, int>> edges;
vector<bool> vis;
vector<int> dp, dep, start_below;
vector<int> start, en;
vector<pair<int, int>> back_edges; // alignment of the edges // 0 is don't flip
string ans;

void dfs(int u, int edgeID, int d = 0) {
	// cout << pl(u) << endl;
	if (vis[u]) return;
	vis[u] = 1;
	dep[u] = d;

	start_below[u] = start[u] - en[u];

	// cout << pl(u) << adj[u] << endl;

	for (auto [v, id] : adj[u]) {
		if (id == edgeID) continue;

		if (!vis[v]) {
			dfs(v, id, d + 1);

			start_below[u] += start_below[v];
			dp[u] += dp[v];
		} else {
			if (dep[u] > dep[v]) {
				// goes up
				dp[u]++;
			} else {
				dp[u]--;
			}
		}
	}

	// cout << pl(u) << pl(dp[u]) << endl;

	if (edgeID != -1 && dp[u] == 0) {
		// back edge
		if (start_below[u] != 0) {
			bool dir = start_below[u] > 0;
			// check what direction the edge was originally oriented
			if (edges[edgeID].first == u) {
				dir = !dir;
			}
			back_edges.emplace_back(edgeID, dir);
		}
	}
}

void solve() {
	int n, m; cin >> n >> m;

	adj.resize(n);
	// dfsTree.resize(n);
	vis.resize(n);
	start_below.resize(n);
	dp.resize(n);
	start.resize(n);
	en.resize(n);
	dep.resize(n);

	for (int i = 0; i < m; i++) {
		int a, b; cin >> a >> b;
		a--, b--;
		if (a == b) continue;
		edges.emplace_back(a, b);
		adj[a].emplace_back(b, i);
		adj[b].emplace_back(a, i);
	}

	int p; cin >> p;

	for (int i = 0; i < p; i++) {
		int a, b; cin >> a >> b;

		a--, b--;
		start[a]++;
		en[b]++;
	}

	for (int i = 0; i < n; i++) if (!vis[i]) dfs(i, -1, 0);

	// cout << pl(vis[1]) << endl;

	ans = string(m, 'B');

	for (auto [edge, dir] : back_edges) {
		ans[edge] = (!dir ? 'R' : 'L');
	}

	cout << ans << endl;
}

int main() {
	// freopen(".in", "r", stdin);
	// freopen(".out", "w", stdout);

	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	int T = 1;
	// cin >> T;
	while (T--)
		solve();
}

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 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 468 KB Output is correct
6 Correct 1 ms 328 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 328 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 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 468 KB Output is correct
6 Correct 1 ms 328 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 328 KB Output is correct
11 Correct 34 ms 7064 KB Output is correct
12 Correct 33 ms 8316 KB Output is correct
13 Correct 41 ms 10048 KB Output is correct
14 Correct 48 ms 11632 KB Output is correct
15 Correct 47 ms 11960 KB Output is correct
16 Correct 44 ms 10420 KB Output is correct
17 Correct 58 ms 12776 KB Output is correct
18 Correct 43 ms 10576 KB Output is correct
19 Correct 44 ms 13828 KB Output is correct
20 Correct 35 ms 8556 KB Output is correct
21 Correct 39 ms 8256 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 0 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 468 KB Output is correct
6 Correct 1 ms 328 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 328 KB Output is correct
11 Correct 34 ms 7064 KB Output is correct
12 Correct 33 ms 8316 KB Output is correct
13 Correct 41 ms 10048 KB Output is correct
14 Correct 48 ms 11632 KB Output is correct
15 Correct 47 ms 11960 KB Output is correct
16 Correct 44 ms 10420 KB Output is correct
17 Correct 58 ms 12776 KB Output is correct
18 Correct 43 ms 10576 KB Output is correct
19 Correct 44 ms 13828 KB Output is correct
20 Correct 35 ms 8556 KB Output is correct
21 Correct 39 ms 8256 KB Output is correct
22 Correct 60 ms 14440 KB Output is correct
23 Correct 64 ms 12848 KB Output is correct
24 Correct 70 ms 12964 KB Output is correct
25 Correct 60 ms 17460 KB Output is correct
26 Correct 63 ms 14124 KB Output is correct
27 Correct 60 ms 12972 KB Output is correct
28 Correct 25 ms 4476 KB Output is correct
29 Correct 48 ms 9276 KB Output is correct
30 Correct 50 ms 9448 KB Output is correct
31 Correct 53 ms 9712 KB Output is correct
32 Correct 58 ms 12436 KB Output is correct