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Submission #1025136

# Submission time Handle Problem Language Result Execution time Memory
1025136 2024-07-16T16:24:29 Z Szil One-Way Streets (CEOI17_oneway) C++17
100 / 100
 113 ms 51496 KB 
#include <bits/stdc++.h>
using namespace std;

const int MAXN = 500'001;
const int K = 21;

vector<pair<int, int>> g[MAXN], g2[MAXN];
int l[MAXN], tin[MAXN], timer = 1, cc = 0, comp[MAXN], be[MAXN], ki[MAXN], up[MAXN][K], fel[MAXN], le[MAXN], U[MAXN], V[MAXN];
char ans[MAXN];
bool is_bridge[MAXN], vis[MAXN];

void dfs(int u, int p = -1) {
	l[u] = tin[u] = timer++;
	vis[u] = 1;
	for (auto [v, idx] : g[u]) {
		if (idx == p) continue;
		if (tin[v]) {
			l[u] = min(l[u], tin[v]);
		} else {
			dfs(v, idx);
			l[u] = min(l[u], l[v]);
			if (l[v] > tin[u]) {
				is_bridge[idx] = 1;
			}
		}
	}
}

void dfs2(int u) {
	vis[u] = 1;
	comp[u] = cc;
	for (auto [v, idx] : g[u]) {
		if (is_bridge[idx] || comp[v]) continue;
		dfs2(v);
	}
}

void dfs3(int u, int p = -1) {
	vis[u] = 1;
	if (p != -1) {
		up[u][0] = p;
	}
	be[u] = timer++;
	for (auto [v, idx] : g2[u]) {
		if (v == p) continue;
		dfs3(v, u);
	}
	ki[u] = timer++;
}

bool is_ancestor(int u, int v) {
	return be[u] <= be[v] && ki[v] <= ki[u];
}

int lca(int u, int v) {
	if (is_ancestor(u, v)) return u;
	if (is_ancestor(v, u)) return v;
	for (int i = K-1; i >= 0; i--) {
		if (up[u][i] && !is_ancestor(up[u][i], v)) u = up[u][i];
	}
	return up[u][0];
}

pair<int, int> dfs4(int u, int p = -1) {
	vis[u] = 1;
	int x = 0, y = 0;
	for (auto [v, idx] : g2[u]) {
		if (v == p) continue;
		auto [a, b] = dfs4(v, u);
		if (a == 0 && b == 0) ans[idx] = 'B';
		else if (a) ans[idx] = v == comp[V[idx]] ? 'L' : 'R';
		else if (b) ans[idx] = v == comp[V[idx]] ? 'R' : 'L';
		x += a; y += b;
	}
	return {x + fel[u], y + le[u]};
}

int main() {
	ios::sync_with_stdio(0); cin.tie(0);
	int n, m; cin >> n >> m;
	for (int i = 1; i <= m; i++) {
		cin >> U[i] >> V[i];
		g[U[i]].emplace_back(V[i], i);
		g[V[i]].emplace_back(U[i], i);
	}

	fill(vis, vis+MAXN, 0);
	for (int i = 1; i <= n; i++) {
		if (!vis[i]) dfs(i);
	}
	
	for (int i = 1; i <= n; i++) {
		if (!comp[i]) {
			cc++;
			dfs2(i);
		}
	}
	
	for (int i = 1; i <= n; i++) {
		for (auto [v, idx] : g[i]) {
			if (comp[v] != comp[i]) {
				g2[comp[i]].emplace_back(comp[v], idx);
			} else {
				ans[idx] = 'B';
			}
		}
	}

	fill(vis, vis+MAXN, 0);
	for (int i = 1; i <= n; i++) {
		if (!vis[i]) dfs3(i);
	}

	for (int k = 1; k < K; k++) {
		for (int i = 1; i <= cc; i++) {
			up[i][k] = up[up[i][k-1]][k-1];
		}
	}

	int q; cin >> q;
	while (q--) {
		int u, v; cin >> u >> v;
		u = comp[u]; v = comp[v];
		int x = lca(u, v);
		fel[u]++;
		le[v]++;
		fel[x]--;
		le[x]--;
	}


	fill(vis, vis+MAXN, 0);
	for (int i = 1; i <= n; i++) {
		if (!vis[i]) dfs4(i);
	}

	for (int i = 1; i <= m; i++) {
		cout << ans[i];
	}
	cout << "\n";
	return 0;
}

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 24412 KB Output is correct
2 Correct 11 ms 24512 KB Output is correct
3 Correct 9 ms 24616 KB Output is correct
4 Correct 12 ms 24668 KB Output is correct
5 Correct 18 ms 24668 KB Output is correct
6 Correct 10 ms 24408 KB Output is correct
7 Correct 13 ms 24664 KB Output is correct
8 Correct 16 ms 24668 KB Output is correct
9 Correct 11 ms 24424 KB Output is correct
10 Correct 10 ms 24412 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 24412 KB Output is correct
2 Correct 11 ms 24512 KB Output is correct
3 Correct 9 ms 24616 KB Output is correct
4 Correct 12 ms 24668 KB Output is correct
5 Correct 18 ms 24668 KB Output is correct
6 Correct 10 ms 24408 KB Output is correct
7 Correct 13 ms 24664 KB Output is correct
8 Correct 16 ms 24668 KB Output is correct
9 Correct 11 ms 24424 KB Output is correct
10 Correct 10 ms 24412 KB Output is correct
11 Correct 38 ms 30800 KB Output is correct
12 Correct 46 ms 31824 KB Output is correct
13 Correct 48 ms 33620 KB Output is correct
14 Correct 61 ms 37052 KB Output is correct
15 Correct 62 ms 38484 KB Output is correct
16 Correct 70 ms 44376 KB Output is correct
17 Correct 72 ms 46420 KB Output is correct
18 Correct 67 ms 44884 KB Output is correct
19 Correct 76 ms 48216 KB Output is correct
20 Correct 42 ms 31576 KB Output is correct
21 Correct 38 ms 31308 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 24412 KB Output is correct
2 Correct 11 ms 24512 KB Output is correct
3 Correct 9 ms 24616 KB Output is correct
4 Correct 12 ms 24668 KB Output is correct
5 Correct 18 ms 24668 KB Output is correct
6 Correct 10 ms 24408 KB Output is correct
7 Correct 13 ms 24664 KB Output is correct
8 Correct 16 ms 24668 KB Output is correct
9 Correct 11 ms 24424 KB Output is correct
10 Correct 10 ms 24412 KB Output is correct
11 Correct 38 ms 30800 KB Output is correct
12 Correct 46 ms 31824 KB Output is correct
13 Correct 48 ms 33620 KB Output is correct
14 Correct 61 ms 37052 KB Output is correct
15 Correct 62 ms 38484 KB Output is correct
16 Correct 70 ms 44376 KB Output is correct
17 Correct 72 ms 46420 KB Output is correct
18 Correct 67 ms 44884 KB Output is correct
19 Correct 76 ms 48216 KB Output is correct
20 Correct 42 ms 31576 KB Output is correct
21 Correct 38 ms 31308 KB Output is correct
22 Correct 113 ms 47956 KB Output is correct
23 Correct 106 ms 46008 KB Output is correct
24 Correct 87 ms 46160 KB Output is correct
25 Correct 113 ms 51496 KB Output is correct
26 Correct 104 ms 47540 KB Output is correct
27 Correct 101 ms 46164 KB Output is correct
28 Correct 31 ms 28752 KB Output is correct
29 Correct 51 ms 32396 KB Output is correct
30 Correct 52 ms 32600 KB Output is correct
31 Correct 48 ms 32624 KB Output is correct
32 Correct 69 ms 38484 KB Output is correct