제출 #914005

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
914005		VMaksimoski008	Railway (BOI17_railway)	C++14	100 / 100	85 ms	24604 KiB

railway

#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;

const short LOG = 17;
const int maxn = 1e5 + 5;

struct BIT {
    int n;
    vector<int> 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;
    }

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

    int 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, i, j;
int depth[maxn+1], up[maxn+1][LOG], in[maxn+1], out[maxn+1];
vector<vector<int> > graph;

void dfs(int u, int p) {
    in[u] = timer++;
    for(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;
}

int jmp(int x, int d) {
    for(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(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() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

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

    vector<pii> edges;
    
    for(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);

    int edge_id[n+1];
    for(i=0; i<n-1; i++) {
        if(depth[edges[i].first] > depth[edges[i].second]) swap(edges[i].first, edges[i].second);
        edge_id[edges[i].second] = i+1;
    }

    BIT bit;
    bit.config(n);

    int cnt;
    int v[n+1];
    while(m--) {
        cin >> cnt;
        for(i=0; i<cnt; i++) cin >> v[i];

        sort(v, v + cnt, [&](int &a, int &b) { return in[a] < in[b]; });
        v[cnt] = v[0];

        int a, b, lca;
        for(i=0; i<cnt; i++) {
            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(i=1; i<=n; i++)
        if(bit.query(in[i], out[i]-1) >= 2 * k) ans.push_back(edge_id[i]);

    cout << ans.size() << '\n';
    sort(ans.begin(), ans.end());
    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