Submission #1083811

#	Time	Username	Problem	Language	Result	Execution time	Memory
1083811		thangdz2k7	Railway (BOI17_railway)	C++17	100 / 100	189 ms	47816 KiB

railway

// author : thembululquaUwU
// 3.9.2024

#include <bits/stdc++.h>
#define pb push_back
#define fi first
#define se second
#define endl '\n'

using namespace std;
using ll = long long;
using ii = pair <int, int>;
using vi = vector <int>;

const int MaxN = 2e5;
const int mod = 1e9 + 7;

void maxl(auto &a, auto b) {a = max(a, b);}
void minl(auto &a, auto b) {a = min(a, b);}

struct LCA{
    vi st, ed, _lg, high, par, ans, a, b, labp;
    vector <vi> euler, adj;
    int cnt;

    void dfs(int u, int pa){
        ++ cnt;
        st[u] = cnt;
        euler[cnt].pb(u);
        for (int id : adj[u]){
            int v = a[id] ^ b[id] ^ u;
            if (v == pa) {
                labp[u] = id;
                continue;
            }
            high[v] = high[u] + 1;
            dfs(v, u);
            euler[++ cnt].pb(u);
        }
        ed[u] = cnt;
    }

    int check(int u, int v) {
        return st[u] <= st[v] && ed[v] <= ed[u];
    }

    int min_by_time(int u, int v) {
        return (st[u] < st[v] ? u : v);
    }

    void add(int u, int v){
        a.pb(u);
        b.pb(v);
        adj[u].pb(a.size() - 1);
        adj[v].pb(a.size() - 1);
    }

    LCA(int n){
        st.resize(n + 3, 0);
        par.resize(n + 3, 0);
        labp.resize(n + 3, 0);
        ans.resize(n + 3, 0);
        ed.resize(n + 3, 0);
        euler.resize(2 * n + 5);
        adj.resize(n + 3);
        _lg.resize(2 * n + 5);
        high.resize(n + 3, 1);
        for (int i = 0; i <= 2 * n; ++ i) _lg[i] = log2(i);
    }

    int get(int u, int v) {
        int L = min(st[u], st[v]);
        int R = max(ed[u], ed[v]);
        int lg = _lg[R - L + 1];
        return min_by_time(euler[L][lg], euler[R - (1 << lg) + 1][lg]);
    }

    void init(int r){
        cnt = 0;
        dfs(r, 0);
        for (int lg = 1; lg < 20; ++lg) {
            for (int i = 1; i + (1 << lg) - 1 <= cnt; ++i)
                euler[i].pb(min_by_time(euler[i][lg - 1], euler[i + (1 << lg - 1)][lg - 1]));
        }
    }

    int dist(int u, int v){
        int lc = get(u, v);
        return high[u] + high[v] - 2 * high[lc];
    }

    #define all(x) (x).begin(), (x).end()
    #define rall(x) (x).rbegin(), (x).rend()
    #define fd(sr, x) (lower_bound(sr.begin(), sr.end(), x) - sr.begin())
    #define uq(sr) (sr).erase(unique(all((sr))), (sr).end())

    void process(vector <int> s){
        int n = s.size();
        sort(all(s), [&](int u, int v){
            return st[u] < st[v];
        });
        for (int i = 1; i < n; ++ i) s.pb(get(s[i], s[i - 1]));
        sort(all(s), [&](int u, int v){
            return st[u] < st[v];
        });
        uq(s); vi st;
        reverse(all(s));
        for (int u : s){
            while (st.size() && check(u, st.back())){
                par[st.back()] = u;
                ans[st.back()] ++;
                ans[u] --;
                st.pop_back();
            }
            st.push_back(u);
        }
    }

    void last(int u, int pa){
        for (int id : adj[u]){
            int v = a[id] ^ b[id] ^ u;
            if (v ^ pa) {
                last(v, u);
                ans[u] += ans[v];
            }
        }
    }
};

void solve(){
    int n, m, k; cin >> n >> m >> k;
    LCA tree(n);
    for (int i = 1, a, b; i < n; ++ i) cin >> a >> b, tree.add(a, b);
    tree.init(1);
    while (m --) {
        int t; cin >> t;
        vi s; while (t --){
            int a; cin >> a; s.pb(a);
        }
        tree.process(s);
    }
    tree.last(1, 0); int ans = 0; vi used(n - 1, 0);
    for (int i = 1; i <= n; ++ i) if (tree.ans[i] >= k) {++ ans; used[tree.labp[i]] = 1;}
    cout << ans << '\n';
    for (int i = 0; i < n - 1; ++ i) if (used[i]) {
        -- ans;
        cout << i + 1;
        if (ans) cout << ' ';
    }
}

int main(){
    if (fopen("railway.inp", "r")){
        freopen("railway.inp", "r", stdin);
        freopen("railway.out", "w", stdout);
    }
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    int t = 1; // cin >> t;
    while (t --) solve();
    return 0;
}

Compilation message (stderr)

railway.cpp:18:11: warning: use of 'auto' in parameter declaration only available with '-fconcepts-ts'
   18 | void maxl(auto &a, auto b) {a = max(a, b);}
      |           ^~~~
railway.cpp:18:20: warning: use of 'auto' in parameter declaration only available with '-fconcepts-ts'
   18 | void maxl(auto &a, auto b) {a = max(a, b);}
      |                    ^~~~
railway.cpp:19:11: warning: use of 'auto' in parameter declaration only available with '-fconcepts-ts'
   19 | void minl(auto &a, auto b) {a = min(a, b);}
      |           ^~~~
railway.cpp:19:20: warning: use of 'auto' in parameter declaration only available with '-fconcepts-ts'
   19 | void minl(auto &a, auto b) {a = min(a, b);}
      |                    ^~~~
railway.cpp: In member function 'void LCA::init(int)':
railway.cpp:83:78: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
   83 |                 euler[i].pb(min_by_time(euler[i][lg - 1], euler[i + (1 << lg - 1)][lg - 1]));
      |                                                                           ~~~^~~
railway.cpp: In function 'int main()':
railway.cpp:154:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  154 |         freopen("railway.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
railway.cpp:155:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  155 |         freopen("railway.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 7 / 7
• Subtask 4: 29 / 29
• Subtask 5: 16 / 16
• Subtask 6: 25 / 25