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Submission #881876

# Submission time Handle Problem Language Result Execution time Memory
881876 2023-12-02T06:57:56 Z Sharky One-Way Streets (CEOI17_oneway) C++17
60 / 100
 3000 ms 32848 KB 
#include <bits/stdc++.h>
using namespace std;

const int N = 100010;
const int lg = 18;

#define fi first
#define se second

vector<pair<int, int>> adj[N];
pair<int, int> edges[N];
set<int> b;
vector<char> ans(N, 'B');
int n, m, pairs, low[N], st[N], timer = 0, k = 0, bcc[N], road_id = 0, lift[N][lg], dep[N], pa[N];
pair<int, int> up[N], down[N];
bool vis[N];

struct edge {
    int v, id;
    char dir;
};

vector<edge> g[N];

void dfs(int u, int p) {
    low[u] = st[u] = ++timer;
    for (auto& [v, id] : adj[u]) {
        if (!st[v]) {
            dfs(v, id);
            low[u] = min(low[u], low[v]);
            if (low[v] > st[u]) b.insert(id);
        } else if (id != p) {
            low[u] = min(low[u], st[v]);
        }
    }
}

void Dfs(int u) {
    bcc[u] = k;
    for (auto& [v, id] : adj[u]) {
        if (b.count(id)) continue;
        if (!bcc[v]) Dfs(v);
    }
}

void pre(int u) {
    vis[u] = 1;
    for (int i = 1; i < lg; i++) lift[u][i] = lift[lift[u][i - 1]][i - 1];
    for (auto& [v, id, dir] : g[u]) {
        if (lift[u][0] != v) {
            dep[v] = dep[u] + 1;
            pa[v] = u;
            lift[v][0] = u;
            pre(v);
        }
    }
}

int jump(int sta, int dist) {
    for (int i = lg - 1; i >= 0; i--) if (dist & (1 << i)) sta = lift[sta][i];
    return sta;
}

int get_lca(int u, int v) {
    if (dep[u] > dep[v]) swap(u, v);
    v = jump(v, dep[v] - dep[u]);
    if (u == v) return u;
    for (int i = lg - 1; i >= 0; i--) {
        int ut = lift[u][i], vt = lift[v][i];
        if (ut != vt) u = ut, v = vt;
    }
    return lift[u][0];
}

int32_t main() {
    ios::sync_with_stdio(0); cin.tie(0);
    cin >> n >> m;
    for (int i = 0, u, v; i < m; i++) {
        cin >> u >> v;
        road_id++;
        adj[u].push_back({v, road_id});
        adj[v].push_back({u, road_id});
        edges[road_id] = {u, v};
    }
    for (int i = 1; i <= n; i++) if (!st[i]) dfs(i, 0);
    for (int i = 1; i <= n; i++) {
        if (!bcc[i]) {
            k++;
            Dfs(i);
        }
    }
    for (int i = 1; i <= m; i++) {
        int u = bcc[edges[i].fi], v = bcc[edges[i].se];
        if (u == v) continue;
        g[u].push_back((edge) {v, i, 'R'});
        g[v].push_back((edge) {u, i, 'L'});
    }
    for (int i = 1; i <= n; i++) if (!vis[i]) {
        lift[i][0] = 1;
        pre(i);
    }
    for (int i = 1; i <= m; i++) {
        int u = bcc[edges[i].fi], v = bcc[edges[i].se];
        if (u == v) continue;
        if (dep[u] > dep[v]) up[u] = {i, 'R'};
        else up[v] = {i, 'L'};
    }
    cin >> pairs;
    while (pairs--) {
        int u, v;
        cin >> u >> v;
        u = bcc[u], v = bcc[v];
        int lca = get_lca(u, v);
        while (u != lca) ans[up[u].first] = up[u].second, u = pa[u];
        while (v != lca) ans[up[v].first] = (up[v].second == 'R' ? 'L' : 'R'), v = pa[v];
    }
    for (int i = 1; i <= m; i++) cout << ans[i];
    cout << '\n';
}

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 10332 KB Output is correct
2 Correct 2 ms 10332 KB Output is correct
3 Correct 3 ms 10588 KB Output is correct
4 Correct 3 ms 10588 KB Output is correct
5 Correct 3 ms 10588 KB Output is correct
6 Correct 2 ms 10588 KB Output is correct
7 Correct 3 ms 10588 KB Output is correct
8 Correct 3 ms 10588 KB Output is correct
9 Correct 2 ms 10588 KB Output is correct
10 Correct 2 ms 10588 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 10332 KB Output is correct
2 Correct 2 ms 10332 KB Output is correct
3 Correct 3 ms 10588 KB Output is correct
4 Correct 3 ms 10588 KB Output is correct
5 Correct 3 ms 10588 KB Output is correct
6 Correct 2 ms 10588 KB Output is correct
7 Correct 3 ms 10588 KB Output is correct
8 Correct 3 ms 10588 KB Output is correct
9 Correct 2 ms 10588 KB Output is correct
10 Correct 2 ms 10588 KB Output is correct
11 Correct 28 ms 14420 KB Output is correct
12 Correct 41 ms 17236 KB Output is correct
13 Correct 54 ms 18000 KB Output is correct
14 Correct 71 ms 22096 KB Output is correct
15 Correct 78 ms 23440 KB Output is correct
16 Correct 120 ms 30548 KB Output is correct
17 Correct 125 ms 31876 KB Output is correct
18 Correct 120 ms 30612 KB Output is correct
19 Correct 126 ms 32848 KB Output is correct
20 Correct 37 ms 18000 KB Output is correct
21 Correct 33 ms 17752 KB Output is correct

Subtask #3
0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 10332 KB Output is correct
2 Correct 2 ms 10332 KB Output is correct
3 Correct 3 ms 10588 KB Output is correct
4 Correct 3 ms 10588 KB Output is correct
5 Correct 3 ms 10588 KB Output is correct
6 Correct 2 ms 10588 KB Output is correct
7 Correct 3 ms 10588 KB Output is correct
8 Correct 3 ms 10588 KB Output is correct
9 Correct 2 ms 10588 KB Output is correct
10 Correct 2 ms 10588 KB Output is correct
11 Correct 28 ms 14420 KB Output is correct
12 Correct 41 ms 17236 KB Output is correct
13 Correct 54 ms 18000 KB Output is correct
14 Correct 71 ms 22096 KB Output is correct
15 Correct 78 ms 23440 KB Output is correct
16 Correct 120 ms 30548 KB Output is correct
17 Correct 125 ms 31876 KB Output is correct
18 Correct 120 ms 30612 KB Output is correct
19 Correct 126 ms 32848 KB Output is correct
20 Correct 37 ms 18000 KB Output is correct
21 Correct 33 ms 17752 KB Output is correct
22 Execution timed out 3034 ms 32004 KB Time limit exceeded
23 Halted 0 ms 0 KB -