| # | Submission time | Handle | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 953504 | 2024-03-26T04:53:14 Z | eysbutno | Railway (BOI17_railway) | C++11 | 0 ms | 0 KB |
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define all(x) begin(x), end(x)
#define sz(x) (int) (x).size()
#define f first
#define s second
template<class T> bool smin(T& a, T b) {
return b < a ? a = b, 1 : 0;
}
template<class T> bool smax(T& a, T b) {
return b > a ? a = b, 1 : 0;
}
template<class T> class FenwickTree {
private:
int sz; vector<T> arr;
public:
FenwickTree(int n) {
sz = n + 1, arr.resize(n + 1);
}
FenwickTree() {} // empty init
T prefix(int idx) {
T tot = 0;
for (++idx; idx >= 1; idx -= idx & -idx) {
tot += arr[idx];
}
return tot;
}
T query(int l, int r) {
return prefix(r) - prefix(l - 1);
}
void update(int idx, T dx) {
for (++idx; idx < sz; idx += idx & -idx) {
arr[idx] += dx;
}
}
};
void solve() {
int n, m, k;
cin >> n >> m >> k;
vector<vector<pii>> adj(n);
for (int i = 1; i < n; i++) {
int u, v; cin >> u >> v;
adj[--u].push_back({--v, i});
adj[v].push_back({u, i});
}
int timer = 0, LOG = 17;
vector<int> tin(n), tout(n),
taken(n);
vector up(LOG, vector(n, 0));
auto tour = [&](int u, int p, auto&& tour) -> void {
tin[u] = timer++;
for (int i = 1; i < LOG; i++) {
up[i][u] = up[i - 1][up[i - 1][u]];
}
for (auto [v, id] : adj[u]) if (v != p) {
// might need more stuff, just this for now.
up[0][v] = u, taken[v] = id;
tour(v, u, tour);
}
tout[u] = timer - 1;
}; tour(0, -1, tour);
auto isAncestor = [&](int a, int b) -> bool {
return tin[a] <= tin[b] && tout[a] >= tout[b];
};
auto lca = [&](int u, int v) -> int {
if (isAncestor(u, v)) return u;
for (int i = LOG - 1; i >= 0; i--) {
if (!isAncestor(up[i][u], v)) {
u = up[i][u];
}
}
return up[0][u];
};
FenwickTree<int> added(timer);
for (int i = 0; i < m; i++) {
int z; cin >> z;
vector<int> cur(z);
for (int &i : cur) {
cin >> i, --i;
}
sort(all(cur), [&](int x, int y) {
return tin[x] < tin[y];
});
cur.push_back(cur[0]);
for (int j = 0; j < z; j++) {
int anc = lca(cur[j], cur[j + 1]);
added.update(tin[cur[j]], 1);
added.update(tin[cur[j + 1]], 1);
added.update(tin[anc], -2);
}
}
vector<int> res;
for (int i = 1; i < n; i++) {
if (added.query(tin[i], tout[i]) >= k * 2) {
res.push_back(taken[i]);
}
}
sort(all(res));
cout << sz(res) << "\n";
for (int i = 0; i < sz(res); i++) {
cout << res[i] << " \n"[i == sz(res) - 1];
}
}
int main() {
cin.tie(0) -> sync_with_stdio(0);
int t = 1; // cin >> t;
while (t--) solve();
}