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Submission #1074887

# Submission time Handle Problem Language Result Execution time Memory
1074887 2024-08-25T16:05:57 Z pqthangv One-Way Streets (CEOI17_oneway) C++11
100 / 100
 65 ms 27496 KB 
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int INF = 1e9 + 5;
const ll oo = 1e18 + 5;

const int MAXN = 1e5 + 5;
const int LOG = 16;

//#define int ll

int n, m, TimerDFS, low[MAXN], num[MAXN], scc_quanity, scc_id[MAXN], par[MAXN][LOG + 1], ans[MAXN];
int high[MAXN], f[MAXN];
pair<int, int> edges[MAXN], e[MAXN];
vector<pair<int, int>> adj[MAXN];
vector<pair<int, int>> g[MAXN];
bool del[MAXN];
bool vis[MAXN];
stack<int> st;

void DFS_tarjan(int u, int pid) {
    ++TimerDFS;
    st.push(u);
//    cout << u << '\n';
    num[u] = low[u] = TimerDFS;
    for (int i = 0; i < int(adj[u].size()); ++i) {
        int v = adj[u][i].first, nid = adj[u][i].second;
        if (pid != nid && del[v] == false){
            if (num[v] == 0) {
                DFS_tarjan(v, nid);
                low[u] = min(low[u], low[v]);
            } else low[u] = min(low[u], num[v]);
        }
    }

    if (low[u] == num[u]) {
        int v;
        ++scc_quanity;
        do {
            v = st.top();
            del[v] = true;
            st.pop();
            scc_id[v] = scc_quanity;
        } while (v != u);
    }
}

//void DFS_high(int u, int p) {
//    for (int i = 0; i < int(g[u].size()); ++i) {
//        int v = g[u][i].f;
//        if (v != p) {
//            high[v] = high[u] + 1;
//            par[v][0] = u;
//            DFS_high(v, u);
//        }
//    }
//}

//void prepare_LCA() {
//    high[0] = -1;
//    DFS_high(1, -1);

//    for (int j = 1; j <= LOG; ++j) {
//        for (int i = 1; i <= n; ++i) {
//            par[i][j] = par[par[i][j - 1]][j - 1];
//        }
//    }
////}
//int LCA(int u, int v) {
//    if (high[u] < high[v]) return LCA(v, u);
//
//    int k = high[u] - high[v];
//
//    for (int i = 0; i <= LOG; ++i) {
//        if ((k >> i) & 1) {
//            u = par[u][i];
//        }
//    }
//
//    if (u == v) return u;
//
//    for (int i = LOG; i >= 0; --i) {
//        if (par[u][i] != par[v][i]) {
//            u = par[u][i];
//            v = par[v][i];
//        }
//    }
//    return par[u][0];
//}

void DFS_solve(int u, int p) {
    vis[u] = true;
    for (int i = 0; i < int(g[u].size()); ++i) {
        int v = g[u][i].first, id = g[u][i].second;
        if (v != p) {
            if (!vis[v])
                DFS_solve(v, u);
            f[u] += f[v];
            if (f[v] == 0) ans[id] = 0;
            else if (f[v] < 0) ans[id] = (v == e[id].second ? 2 : 1);
            else ans[id] = (v == e[id].second ? 1 : 2);
        }
    }
}

void solve()
{
    cin >> n >> m;
    for (int i = 1; i <= m; ++i) {
        int u, v; cin >> u >> v;
        adj[u].push_back({v, i});
        adj[v].push_back({u, i});
        edges[i] = {u, v};
    }
    for (int i = 1; i <= n; ++i)
        if (num[i] == 0) DFS_tarjan(i, -1);
//    cout << TimerDFS << '\n';
//    cout << scc_quanity << '\n';
//    for (int i = 1; i <= n; ++i) {
//        cout << scc_id[i] << ' ';
//    }
//    cout << '\n';

    for (int i = 1; i <= m; ++i) {
        int u = scc_id[edges[i].first], v = scc_id[edges[i].second];
        // vi la vo huong nen ko co canh trung
        if (u != v) {
            g[u].push_back({v, i});
            g[v].push_back({u, i});
            e[i] = {u, v};
        }
    }
//    for (int i = 1; i <= scc)
//    prepare_LCA();
//    DFS_high(1, -1);
    int q; cin >> q;
    while (q--) {
        int u, v; cin >> u >> v;
        u = scc_id[u];
        v = scc_id[v];
//        int uv = LCA(u, v);
        ++f[u];
        --f[v];
//        cout << u << ' ' << v << '\n';
//        f[uv] -= 3;
    }

    for (int i = 1; i <= scc_quanity; ++i)
        if (!vis[i])
            DFS_solve(i, -1);

    for (int i = 1; i <= m; ++i) {
        if (ans[i] == 0) cout << "B";
        else if (ans[i] == 1) cout << "L";
        else cout << "R";
    }
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(NULL); cout.tie(NULL);

//    freopen("phanluong.inp", "r", stdin);
//    freopen("phanluong.out", "w", stdout);

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

    return 0;
}

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 10588 KB Output is correct
2 Correct 1 ms 10588 KB Output is correct
3 Correct 2 ms 10588 KB Output is correct
4 Correct 2 ms 10588 KB Output is correct
5 Correct 3 ms 10860 KB Output is correct
6 Correct 2 ms 10588 KB Output is correct
7 Correct 1 ms 8680 KB Output is correct
8 Correct 2 ms 10588 KB Output is correct
9 Correct 2 ms 6664 KB Output is correct
10 Correct 2 ms 8540 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 10588 KB Output is correct
2 Correct 1 ms 10588 KB Output is correct
3 Correct 2 ms 10588 KB Output is correct
4 Correct 2 ms 10588 KB Output is correct
5 Correct 3 ms 10860 KB Output is correct
6 Correct 2 ms 10588 KB Output is correct
7 Correct 1 ms 8680 KB Output is correct
8 Correct 2 ms 10588 KB Output is correct
9 Correct 2 ms 6664 KB Output is correct
10 Correct 2 ms 8540 KB Output is correct
11 Correct 30 ms 12120 KB Output is correct
12 Correct 31 ms 16988 KB Output is correct
13 Correct 40 ms 18004 KB Output is correct
14 Correct 36 ms 17232 KB Output is correct
15 Correct 34 ms 16076 KB Output is correct
16 Correct 39 ms 17492 KB Output is correct
17 Correct 40 ms 18860 KB Output is correct
18 Correct 51 ms 17416 KB Output is correct
19 Correct 62 ms 20948 KB Output is correct
20 Correct 27 ms 16476 KB Output is correct
21 Correct 25 ms 16208 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 10588 KB Output is correct
2 Correct 1 ms 10588 KB Output is correct
3 Correct 2 ms 10588 KB Output is correct
4 Correct 2 ms 10588 KB Output is correct
5 Correct 3 ms 10860 KB Output is correct
6 Correct 2 ms 10588 KB Output is correct
7 Correct 1 ms 8680 KB Output is correct
8 Correct 2 ms 10588 KB Output is correct
9 Correct 2 ms 6664 KB Output is correct
10 Correct 2 ms 8540 KB Output is correct
11 Correct 30 ms 12120 KB Output is correct
12 Correct 31 ms 16988 KB Output is correct
13 Correct 40 ms 18004 KB Output is correct
14 Correct 36 ms 17232 KB Output is correct
15 Correct 34 ms 16076 KB Output is correct
16 Correct 39 ms 17492 KB Output is correct
17 Correct 40 ms 18860 KB Output is correct
18 Correct 51 ms 17416 KB Output is correct
19 Correct 62 ms 20948 KB Output is correct
20 Correct 27 ms 16476 KB Output is correct
21 Correct 25 ms 16208 KB Output is correct
22 Correct 51 ms 20048 KB Output is correct
23 Correct 58 ms 18416 KB Output is correct
24 Correct 64 ms 21600 KB Output is correct
25 Correct 58 ms 27496 KB Output is correct
26 Correct 61 ms 21276 KB Output is correct
27 Correct 65 ms 21352 KB Output is correct
28 Correct 22 ms 11968 KB Output is correct
29 Correct 57 ms 15440 KB Output is correct
30 Correct 41 ms 17236 KB Output is correct
31 Correct 36 ms 15964 KB Output is correct
32 Correct 45 ms 20308 KB Output is correct