Submission #914003

#	Time	Username	Problem	Language	Result	Execution time	Memory
914003		VMaksimoski008	Railway (BOI17_railway)	C++14	100 / 100	109 ms	29768 KiB

railway

#include <bits/stdc++.h>

#define pb push_back
#define eb emplace_back
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define uniq(x) x.erase(unique(all(x)), x.end())
#define rall(x) x.rbegin(), x.rend()
//#define int long long

using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

const int mod = 1e9 + 7;
const int LOG = 20;
const int maxn = 1e5 + 5;
const double eps = 1e-9;

void setIO() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
}

struct BIT {
    int n;
    vector<ll> tree, val;

    void config(int _n) {
        n = _n + 10;
        tree.resize(_n+60);
        val.resize(_n+60);
    }

    void add(int p, int v) {
        val[p] += v;
        for(p++; p<n; p+=p&-p) tree[p] += v;
    }

    ll sum(int p) {
        ll ans = 0;
        for(p++; p>0; p-=p&-p) ans += tree[p];
        return ans;
    }

    ll query(int l, int r) { return sum(r) - sum(l-1); }
    void set(int p, int v) { add(p, v - val[p]); }
};

int n, m, k, timer = 0;
int depth[maxn+1], up[maxn+1][LOG], in[maxn+1], out[maxn+1];
vector<vector<int> > graph;
vector<int> euler;

void dfs(int u, int p) {
    in[u] = timer++;
    euler.push_back(u);
    for(int i=1; i<LOG; i++)
        up[u][i] = up[ up[u][i-1] ][i-1];

    for(int &v : graph[u]) {
        if(v == p) continue;
        depth[v] = depth[u] + 1;
        up[v][0] = u;
        dfs(v, u);
    }

    out[u] = timer;
    euler.push_back(u);
}

int jmp(int x, int d) {
    for(int j=LOG-1; j>=0; j--)
        if(d & (1 << j)) x = up[x][j];
    return x;
}

int get_lca(int a, int b) {
    if(depth[a] < depth[b]) swap(a, b);

    a = jmp(a, depth[a] - depth[b]);
    if(a == b) return a;
    for(int j=LOG-1; j>=0; j--)
        if(up[a][j] != up[b][j])
            a = up[a][j], b = up[b][j];

    return up[a][0];
}

int32_t main() {
    setIO();

    cin >> n >> m >> k;
    graph.resize(n+1);

    vector<pii> edges;
    
    for(int i=0; i<n-1; i++) {
        int a, b;
        cin >> a >> b;
        edges.push_back({ a, b });
        graph[a].push_back(b);
        graph[b].push_back(a);
    }

    dfs(1, 0);

    for(pii &x : edges)
        if(depth[x.first] > depth[x.second]) swap(x.first, x.second);

    vector<int> edge_id(n+1);
    for(int i=0; i<n-1; i++)
        edge_id[edges[i].second] = i+1;

    BIT bit;
    bit.config(2*n);

    while(m--) {
        int cnt;
        cin >> cnt;

        vector<int> v(cnt);
        for(int &x : v) cin >> x;

        sort(all(v), [&](int a, int b) { return in[a] < in[b]; });
        v.push_back(v[0]);

        for(int i=0; i<cnt; i++) {
            int a = v[i], b = v[i+1], lca = get_lca(a, b);
            bit.add(in[a], 1);
            bit.add(in[b], 1);
            bit.add(in[lca], -2);
        }
    }


    vector<int> ans;
    for(int i=1; i<=n; i++)
        if(bit.query(in[i], out[i]-1) >= 2 * k) ans.push_back(edge_id[i]);

    cout << sz(ans) << '\n';
    sort(all(ans));
    for(int &x : ans) cout << x << " ";
    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