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Submission #697940

# Submission time Handle Problem Language Result Execution time Memory
697940 2023-02-11T14:01:39 Z dattranxxx One-Way Streets (CEOI17_oneway) C++11
100 / 100
 213 ms 39980 KB 
#include<bits/stdc++.h>
using namespace std;
using ll = long long;

const int N = 1e5 + 5;
vector<pair<int, int>> adj[N], tree[N];
vector<int> bridge;
pair<int, int> edges[N];
int n, m, q;

vector<int> st;
int in[N], low[N], idx[N], id = 0, t = 0;
void dfs(int u, int pe = -1) {
  in[u] = low[u] = ++t;
  st.emplace_back(u);
  for (auto& p : adj[u]) {
    int v, e; tie(v, e) = p;
    if (idx[v] || e == pe) continue;
    if (!in[v]) {
      dfs(v, e);
      low[u] = min(low[u], low[v]);
      if (low[v] > in[u]) bridge.emplace_back(e);
    } else {
      low[u] = min(low[u], in[v]);
    }  
  }
  if (low[u] == in[u]) {
    idx[u] = ++id;
    while (!st.empty()) {
      int v = st.back(); st.pop_back();
      idx[v] = idx[u];
      if (v == u) break;
    }
  }
}

int dep[N], par[N][20];
void dfs2(int u, int p = 0) {
  dep[u] = dep[p] + 1;
  par[u][0] = p;
  for (int i = 1; i < 20; ++i)
    par[u][i] = par[par[u][i - 1]][i - 1];
  
  for (auto& pi : tree[u]) {
    int v, e; tie(v, e) = pi;
    if (v == p) continue;
    dfs2(v, u);
  }
}

int lca(int u, int v) {
  if (dep[u] <= dep[v]) swap(u, v);
  for (int i = 19; ~i; --i) if (dep[par[u][i]] >= dep[v]) u = par[u][i];
  if (u == v) return u;
  for (int i = 19; ~i; --i) if (par[u][i] != par[v][i])
    u = par[u][i], v = par[v][i];
  return par[u][0];
}

int dir[N][20];
int ans[N];

int main() {
  cin.tie(0)->sync_with_stdio(0); cout.tie(0);
  cin >> n >> m;
  for (int i = 0, u, v; i < m; ++i) {
    cin >> u >> v;
    adj[u].emplace_back(v, i);
    adj[v].emplace_back(u, i);
    edges[i] = {u, v};
  }
  for (int i = 1; i <= n; ++i)
    if (!in[i]) dfs(i);
  for (auto& i : bridge) {
    int u, v; tie(u, v) = edges[i];
    u = idx[u], v = idx[v];
    tree[u].emplace_back(v, i);
    tree[v].emplace_back(u, i);
  }
  for (int i = 1; i <= n; ++i) {
    sort(tree[i].begin(), tree[i].end());
    tree[i].erase(unique(tree[i].begin(), tree[i].end()), tree[i].end());
  }
  
  dep[0] = -1;
  for (int i = 1; i <= id; ++i) 
    if (!par[i][0]) dfs2(i);

  cin >> q;
  for (int i = 0, u, v; i < q; ++i) {
    cin >> u >> v; 
    u = idx[u]; v = idx[v];
    int z = lca(u, v);
    for (int i = 19; ~i; --i) {
      if (dep[par[u][i]] >= dep[z])
        dir[u][i] = 1, u = par[u][i];
      if (dep[par[v][i]] >= dep[z])
        dir[v][i] = 2, v = par[v][i];
     }
  }
  
  for (int i = 19; ~i; --i)  {
    for (int u = 1; u <= id; ++u) if (dir[u][i]) {
      dir[u][i - 1] = dir[u][i];
      dir[par[u][i - 1]][i - 1] = dir[u][i];
    }
  }
  
  for (auto& i : bridge) {
    int u, v; tie(u, v) = edges[i];
    u = idx[u], v = idx[v];
    if (dep[u] > dep[v]) {
      ans[i] = dir[u][0];
    } else {
      if (dir[v][0] == 0) continue;
      ans[i] = 3 - dir[v][0];
    }
  }
  
  for (int i = 0; i < m; ++i) {
    if (!ans[i]) cout << 'B';
    else if (ans[i] == 1) cout << 'R';
    else cout << 'L';
  }
  
	return 0;
}

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 5028 KB Output is correct
2 Correct 3 ms 4948 KB Output is correct
3 Correct 3 ms 5076 KB Output is correct
4 Correct 3 ms 5204 KB Output is correct
5 Correct 3 ms 5380 KB Output is correct
6 Correct 3 ms 5040 KB Output is correct
7 Correct 4 ms 5380 KB Output is correct
8 Correct 5 ms 5292 KB Output is correct
9 Correct 3 ms 5076 KB Output is correct
10 Correct 3 ms 5076 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 5028 KB Output is correct
2 Correct 3 ms 4948 KB Output is correct
3 Correct 3 ms 5076 KB Output is correct
4 Correct 3 ms 5204 KB Output is correct
5 Correct 3 ms 5380 KB Output is correct
6 Correct 3 ms 5040 KB Output is correct
7 Correct 4 ms 5380 KB Output is correct
8 Correct 5 ms 5292 KB Output is correct
9 Correct 3 ms 5076 KB Output is correct
10 Correct 3 ms 5076 KB Output is correct
11 Correct 33 ms 11820 KB Output is correct
12 Correct 42 ms 13324 KB Output is correct
13 Correct 46 ms 15148 KB Output is correct
14 Correct 65 ms 18448 KB Output is correct
15 Correct 70 ms 19732 KB Output is correct
16 Correct 86 ms 24876 KB Output is correct
17 Correct 95 ms 32120 KB Output is correct
18 Correct 77 ms 26872 KB Output is correct
19 Correct 80 ms 34100 KB Output is correct
20 Correct 41 ms 12532 KB Output is correct
21 Correct 37 ms 12564 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 5028 KB Output is correct
2 Correct 3 ms 4948 KB Output is correct
3 Correct 3 ms 5076 KB Output is correct
4 Correct 3 ms 5204 KB Output is correct
5 Correct 3 ms 5380 KB Output is correct
6 Correct 3 ms 5040 KB Output is correct
7 Correct 4 ms 5380 KB Output is correct
8 Correct 5 ms 5292 KB Output is correct
9 Correct 3 ms 5076 KB Output is correct
10 Correct 3 ms 5076 KB Output is correct
11 Correct 33 ms 11820 KB Output is correct
12 Correct 42 ms 13324 KB Output is correct
13 Correct 46 ms 15148 KB Output is correct
14 Correct 65 ms 18448 KB Output is correct
15 Correct 70 ms 19732 KB Output is correct
16 Correct 86 ms 24876 KB Output is correct
17 Correct 95 ms 32120 KB Output is correct
18 Correct 77 ms 26872 KB Output is correct
19 Correct 80 ms 34100 KB Output is correct
20 Correct 41 ms 12532 KB Output is correct
21 Correct 37 ms 12564 KB Output is correct
22 Correct 213 ms 35740 KB Output is correct
23 Correct 169 ms 33552 KB Output is correct
24 Correct 171 ms 33684 KB Output is correct
25 Correct 195 ms 39980 KB Output is correct
26 Correct 169 ms 35284 KB Output is correct
27 Correct 161 ms 33496 KB Output is correct
28 Correct 43 ms 9096 KB Output is correct
29 Correct 73 ms 13000 KB Output is correct
30 Correct 84 ms 13388 KB Output is correct
31 Correct 91 ms 13728 KB Output is correct
32 Correct 106 ms 22436 KB Output is correct