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Submission #411779

# Submission time Handle Problem Language Result Execution time Memory
411779 2021-05-25T23:15:28 Z penguinhacker One-Way Streets (CEOI17_oneway) C++14
100 / 100
 187 ms 30112 KB 
#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define ar array

const int mxN=1e5;
int n, m, k, eu[mxN], ev[mxN], t, ecc, tin[mxN], low[mxN], who[mxN], d[mxN], anc[mxN][17], dp[mxN][2];
vector<int> adj[mxN];
stack<int> st;
vector<ar<int, 2>> br, adj2[mxN];
char ans[mxN];

void make(int u) {
	who[u]=ecc;
	while(st.top()^u)
		who[st.top()]=ecc, st.pop();
	st.pop(), ++ecc;
}

void dfs(int u, int p=-1) {
	tin[u]=low[u]=++t;
	st.push(u);
	for (int i : adj[u]) {
		if (i==p)
			continue;
		int v=u^eu[i]^ev[i];
		if (!tin[v]) {
			dfs(v, i);
			low[u]=min(low[u], low[v]);
			if (low[v]>tin[u]) {
				br.push_back({i, u==eu[i]});
				make(v);
			}
		} else
			low[u]=min(low[u], tin[v]);
	}
}

void dfs2(int u, int p=-1) {
	anc[u][0]=p;
	for (int i=1; i<17; ++i)
		anc[u][i]=anc[u][i-1]^-1?anc[anc[u][i-1]][i-1]:-1;
	for (ar<int, 2> x : adj2[u]) {
		int v=u^who[eu[x[0]]]^who[ev[x[0]]];
		d[v]=d[u]+1;
		dfs2(v, u);
	}
}

int lca(int u, int v) {
	if (d[u]>d[v])
		swap(u, v);
	for (int i=16; ~i; --i)
		if (d[u]<=d[v]-(1<<i))
			v=anc[v][i];
	if (u==v)
		return u;
	for (int i=16; ~i; --i)
		if (anc[u][i]^anc[v][i])
			u=anc[u][i], v=anc[v][i];
	return anc[u][0];
}

void dfs3(int u) {
	for (ar<int, 2> x : adj2[u]) {
		int v=u^who[eu[x[0]]]^who[ev[x[0]]];
		dfs3(v);
		dp[u][0]+=dp[v][0];
		dp[u][1]+=dp[v][1];
		assert(!(dp[v][0]&&dp[v][1]));
		if (dp[v][0]||dp[v][1])
			ans[x[0]]=x[1]^(dp[v][0]>0)?'R':'L';
	}
}

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin >> n >> m;
	for (int i=0; i<m; ++i) {
		cin >> eu[i] >> ev[i], --eu[i], --ev[i];
		if (eu[i]^ev[i]) {
			adj[eu[i]].push_back(i);
			adj[ev[i]].push_back(i);
		}
	}
	for (int i=0; i<n; ++i) {
		if (tin[i])
			continue;
		dfs(i);
		make(i);
		for (ar<int, 2> b : br) {
			int u=b[1]?eu[b[0]]:ev[b[0]];
			adj2[who[u]].push_back(b);
		}
		br.clear();
		dfs2(who[i]);
	}
	cin >> k;
	for (int i=0; i<k; ++i) {
		int u, v;
		cin >> u >> v, --u, --v;
		u=who[u], v=who[v];
		int uv=lca(u, v);
		++dp[u][0], --dp[uv][0];
		++dp[v][1], --dp[uv][1];
	}
	memset(ans, 'B', m);
	for (int i=0; i<ecc; ++i)
		if (anc[i][0]==-1)
			dfs3(i);
	for (int i=0; i<m; ++i)
		cout << ans[i];
	return 0;
}

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4940 KB Output is correct
2 Correct 3 ms 5028 KB Output is correct
3 Correct 4 ms 5068 KB Output is correct
4 Correct 4 ms 5196 KB Output is correct
5 Correct 4 ms 5196 KB Output is correct
6 Correct 4 ms 5068 KB Output is correct
7 Correct 5 ms 5196 KB Output is correct
8 Correct 4 ms 5196 KB Output is correct
9 Correct 4 ms 5068 KB Output is correct
10 Correct 4 ms 5068 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4940 KB Output is correct
2 Correct 3 ms 5028 KB Output is correct
3 Correct 4 ms 5068 KB Output is correct
4 Correct 4 ms 5196 KB Output is correct
5 Correct 4 ms 5196 KB Output is correct
6 Correct 4 ms 5068 KB Output is correct
7 Correct 5 ms 5196 KB Output is correct
8 Correct 4 ms 5196 KB Output is correct
9 Correct 4 ms 5068 KB Output is correct
10 Correct 4 ms 5068 KB Output is correct
11 Correct 44 ms 10560 KB Output is correct
12 Correct 48 ms 11812 KB Output is correct
13 Correct 59 ms 13628 KB Output is correct
14 Correct 75 ms 16484 KB Output is correct
15 Correct 68 ms 17748 KB Output is correct
16 Correct 94 ms 21944 KB Output is correct
17 Correct 88 ms 24620 KB Output is correct
18 Correct 93 ms 21944 KB Output is correct
19 Correct 85 ms 26276 KB Output is correct
20 Correct 49 ms 11560 KB Output is correct
21 Correct 46 ms 11224 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4940 KB Output is correct
2 Correct 3 ms 5028 KB Output is correct
3 Correct 4 ms 5068 KB Output is correct
4 Correct 4 ms 5196 KB Output is correct
5 Correct 4 ms 5196 KB Output is correct
6 Correct 4 ms 5068 KB Output is correct
7 Correct 5 ms 5196 KB Output is correct
8 Correct 4 ms 5196 KB Output is correct
9 Correct 4 ms 5068 KB Output is correct
10 Correct 4 ms 5068 KB Output is correct
11 Correct 44 ms 10560 KB Output is correct
12 Correct 48 ms 11812 KB Output is correct
13 Correct 59 ms 13628 KB Output is correct
14 Correct 75 ms 16484 KB Output is correct
15 Correct 68 ms 17748 KB Output is correct
16 Correct 94 ms 21944 KB Output is correct
17 Correct 88 ms 24620 KB Output is correct
18 Correct 93 ms 21944 KB Output is correct
19 Correct 85 ms 26276 KB Output is correct
20 Correct 49 ms 11560 KB Output is correct
21 Correct 46 ms 11224 KB Output is correct
22 Correct 154 ms 25788 KB Output is correct
23 Correct 155 ms 23392 KB Output is correct
24 Correct 138 ms 23188 KB Output is correct
25 Correct 187 ms 30112 KB Output is correct
26 Correct 154 ms 25168 KB Output is correct
27 Correct 139 ms 23592 KB Output is correct
28 Correct 44 ms 8292 KB Output is correct
29 Correct 78 ms 12068 KB Output is correct
30 Correct 75 ms 12348 KB Output is correct
31 Correct 72 ms 12828 KB Output is correct
32 Correct 102 ms 18916 KB Output is correct