Submission #456326

#	Time	Username	Problem	Language	Result	Execution time	Memory
456326		arujbansal	Rigged Roads (NOI19_riggedroads)	C++17	100 / 100	510 ms	62908 KiB

riggedroads

#include <bits/stdc++.h>

using namespace std;

void dbg_out() { cerr << endl; }
template<typename Head, typename... Tail>
void dbg_out(Head H, Tail... T) { cerr << ' ' << H; dbg_out(T...); }
#define dbg(...) cerr << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)

#define rng_init mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#define rng_seed(x) mt19937 rng(x)
#define all(x) (x).begin(), (x).end()
#define sz(x) (int) (x).size()
// #define int long long

struct UFDS {
    int n;
    vector<int> info;
 
    UFDS() {}
 
    UFDS(int _n) { init(_n); }
 
    void init(int _n) {
        n = _n;
        info.assign(n, -1);
    }
 
    int get(int x) {
        if (info[x] < 0) return x;
        return info[x] = get(info[x]);
    }
 
    bool unite(int x, int y) {
        x = get(x), y = get(y);
        if (x == y) return false;
 
        info[x] += info[y];
        info[y] = x;
 
        return true;    
    }
 
    bool connected(int x, int y) { return get(x) == get(y); }
};

const int MXN = 3e5 + 5, INF = 1e9 + 5, MXK = 21;
int N, E, timer, available_weight, delta;
vector<pair<int, int>> edges;
vector<pair<int, int>> adj_keep[MXN];
bool keep[MXN], mex[MXN];
int tin[MXN], tout[MXN], binlift_par[MXN][MXK], edge_idx[MXN], ans[MXN];
UFDS covering;

void dfs(int u, int p) {
    tin[u] = timer++;

    for (int j = 1; j < MXK; j++)
        binlift_par[u][j] = binlift_par[binlift_par[u][j - 1]][j - 1];

    for (const auto &[v, idx] : adj_keep[u]) {
        if (v == p) continue;

        binlift_par[v][0] = u;

        edge_idx[v] = idx;
        dfs(v, u);
    }

    tout[u] = timer - 1;
}

bool is_anc(int u, int v) {
    return tin[u] <= tin[v] && tout[u] >= tout[v];
}

int query_lca(int u, int v) {
    if (is_anc(u, v)) return u;
    if (is_anc(v, u)) return v;

    for (int j = MXK - 1; j >= 0; j--) {
        int lift = binlift_par[u][j];
        if (is_anc(lift, v)) continue;

        u = lift;
    }

    return binlift_par[u][0];
}

void fill_path(int u, int v) {
    int lca = query_lca(u, v);
    u = covering.get(u), v = covering.get(v);

    vector<int> path_edges;

    while (u != lca && is_anc(lca, u)) {
        path_edges.push_back(edge_idx[u]);
        
        covering.unite(binlift_par[u][0], u);
        u = covering.get(u);
    }

    while (v != lca && is_anc(lca, v)) {
        path_edges.push_back(edge_idx[v]);
        
        covering.unite(binlift_par[v][0], v);
        v = covering.get(v);
    }

    sort(all(path_edges));

    for (const auto &idx : path_edges) {
        if (ans[idx] == 0) ans[idx] = available_weight++;
    }
}

void solve() {
    cin >> N >> E;

    edges.resize(E);
    for (auto &[u, v] : edges) {
        cin >> u >> v;
        u--, v--;
    }

    for (int i = 0; i < N - 1; i++) {
        int idx;
        cin >> idx;
        idx--;

        keep[idx] = true;

        adj_keep[edges[idx].first].emplace_back(edges[idx].second, idx);
        adj_keep[edges[idx].second].emplace_back(edges[idx].first, idx);
    }

    dfs(0, -1);
    available_weight = 1;

    covering.init(N);

    for (int i = 0, j = 1; i < E; i++) {
        if (ans[i] != 0) continue;

        if (!keep[i])
            fill_path(edges[i].first, edges[i].second);

        ans[i] = available_weight++;
    }

    for (int i = 0; i < E; i++)
        cout << ans[i] << " ";
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

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

Compilation message (stderr)

riggedroads.cpp: In function 'void solve()':
riggedroads.cpp:143:21: warning: unused variable 'j' [-Wunused-variable]
  143 |     for (int i = 0, j = 1; i < E; i++) {
      |                     ^

• Subtask 1: 8 / 8
• Subtask 2: 19 / 19
• Subtask 3: 9 / 9
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 12 / 12
• Subtask 7: 32 / 32