Submission #1095835

#	Time	Username	Problem	Language	Result	Execution time	Memory
1095835		anhthi	Railway (BOI17_railway)	C++14	100 / 100	77 ms	28368 KiB

railway

#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define ll long long
#define mp(x, y) make_pair(x, y)
#define sz(v) ((int) (v).size())
#define all(v) (v).begin(), (v).end()
#define MASK(i) (1LL << (i))
#define BIT(x, y) (((x) >> (y)) & 1)
#define pb push_back
#define max_rng *max_element
#define min_rng *min_element
#define rep(i, n) for(int i = 1, _n = (n); i <= _n; ++i)
#define forn(i, a, b) for(int i = (a), _b = (b); i <= _b; ++i)
#define ford(i, a, b) for(int i = (a), _b = (b); i >= _b; --i)

template <class X, class Y>
    inline bool maximize(X &x, Y y) {
        return (x < y ? x = y, true : false);
    }

template <class X, class Y>
    inline bool minimize(X &x, Y y) {
        return (x > y ? x = y, true : false);
    }

template <class X>
    inline void compress(vector<X> &a) {
        sort(all(a));
        a.resize(unique(all(a)) - a.begin());
    }

int ctz(ll x) { return __builtin_ctzll(x); }
int lg(ll x) { return 63 - __builtin_clzll(x); }
int popcount(ll x) { return __builtin_popcount(x); }

mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rand(ll l, ll r) {
    return l + abs((ll) rng()) % (r - l + 1);
}

const ll oo = (ll) 1e17;
const int inf = (ll) 2e9 + 7, mod = (ll) 1e9 + 7;

const int mxn = 1e5 + 5, LOG = 20;

void add(int &x, int y) { x += y; if (x >= mod) x -= mod; }
void sub(int &x, int y) { x -= y; if (x < 0) x += mod; }

int n, m, k;
vector<pair<int, int>> g[mxn];

int timer = 0;
int in[mxn], out[mxn];

int h[mxn];
int par[mxn][LOG + 5];

int cnt[mxn], pf[mxn];

void dfs(int u, int p) {
    par[u][0] = p;
    h[u] = h[p] + 1;
    forn(i, 1, LOG) {
        par[u][i] = par[par[u][i-1]][i-1];
    }

    in[u] = ++timer;
    for (pair<int, int> i : g[u]) if (i.first != p) {
        dfs(i.first, u);
    }
    out[u] = timer;
}
int lift(int u, int k) {
    for (; k > 0; k -= k & -k)
        u = par[u][ctz(k)];
    return u;
}
int lca(int u, int v) {
    if (h[u] < h[v])
        swap(u, v);
    u = lift(u, h[u] - h[v]);
    if (u == v) return u;
    ford(i, lg(h[u]), 0) if (par[u][i] != par[v][i]) {
        u = par[u][i];
        v = par[v][i];
    }
    return par[u][0];
}
bool isIn(int root, int u) {
    return in[root] <= in[u] && in[u] <= out[root];
}
bool compare(int &u, int &v) {
    return in[u] < in[v];
}

void fix(int u = 1, int p = 0) {
    for (pair<int, int> i : g[u]) if (i.first != p) {
        fix(i.first, u);
        pf[u] += pf[i.first];
        cnt[i.second] = pf[i.first];
    }
}

signed main(void) {

    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    cin >> n >> m >> k;
    rep(i, n - 1) {
        int u, v;
        cin >> u >> v;
        g[u].pb(mp(v, i));
        g[v].pb(mp(u, i));
    }

    dfs(1, 0);

    rep(_, m) {
        int k;
        cin >> k;

        vector<int> req(k);
        for (int &i : req) cin >> i;

        sort(all(req), compare);
        forn(i, 0, k - 2) req.pb(lca(req[i], req[i+1]));

        compress(req);
        sort(all(req), compare);

        stack<int> st;
        st.push(req[0]);
        forn(i, 1, sz(req) - 1) {
            int u = req[i];
            while (!st.empty() && !isIn(st.top(), u))
                st.pop();
            if (!st.empty()) {
                pf[st.top()]--;
                pf[u]++;
            }
            st.push(u);
        }
    }

    fix();
    vector<int> res;
    forn(i, 1, n - 1) if (cnt[i] >= k)
        res.pb(i);
    cout << sz(res) << '\n';
    for (int v : res) cout << v << ' ';

    return 0;
}

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