Submission #480697

#	Time	Username	Problem	Language	Result	Execution time	Memory
480697		hidden1	Railway (BOI17_railway)	C++14	0 / 100	111 ms	23748 KiB

railway

#include <bits/stdc++.h>
using namespace std;
//#pragma GCC optimize ("O3")
//#pragma GCC target ("sse4")
#define endl "\n"
typedef long long ll;
template<class T, class T2> inline ostream &operator <<(ostream &out, const pair<T, T2> &x) { out << x.first << " " << x.second; return out;}
template<class T, class T2> inline istream &operator >>(istream &in, pair<T, T2> &x) { in >> x.first >> x.second; return in;}
template<class T, class T2> inline bool chkmax(T &x, const T2 &y) { return x < y ? x = y, 1 : 0; }
template<class T, class T2> inline bool chkmin(T &x, const T2 &y) { return x > y ? x = y, 1 : 0; }
const ll mod = 1e9 + 7;
#ifndef LOCAL
#define cerr if(false) cerr
#endif

const int MAX_N = 1e5 + 10, MAX_LOG = 20;;
vector<pair<int, int> > g[MAX_N];
int par[MAX_N][MAX_LOG];
int d[MAX_N];
int ind[MAX_N], cnt[MAX_N];
vector<int> ans;
int n, m, k;

void dfs(int x, int p) {
    par[x][0] = p;
    for(int i = 1; i < MAX_LOG; i ++) {
        par[x][i] = par[par[x][i - 1]][i - 1];
    }
    d[x] = d[p] + 1;
    for(auto it : g[x]) {
        if(it.first == p) {continue;}
        ind[it.first] = it.second;
        dfs(it.first, x);
    }
}

int lca(int a, int b) {
    if(d[a] < d[b]) {swap(a, b);}
    for(int i = MAX_LOG - 1; i >= 0; i --) {
        if(d[par[a][i]] >= d[b]) {
            a = par[a][i];
        }
    }
    if(a == b) {return a;}
    for(int i = 0; i < MAX_LOG; i ++) {
        if(par[a][i] != par[b][i]) {
            a = par[a][i];
            b = par[b][i];
        }
    }
    return par[a][0];
}

int calc(int x, int p) {
    int now = cnt[x];
    for(auto it : g[x]) {
        if(it.first == p) {continue;}
        now += calc(it.first, x);
    }
    if(now >= k) {
        ans.push_back(ind[x]);
    }
    return now;
}

signed main() {
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
    
    cin >> n >> m >> k;
    for(int i = 0; i < n - 1; i ++) {
        int a, b;
        cin >> a >> b;
        g[a].push_back({b, i + 1});
        g[b].push_back({a, i + 1});
    }
    dfs(1, 0);

    for(int i = 0; i < m; i ++) {
        int lst;
        cin >> lst;
        vector<int> a(lst);
        for(int j = 0; j < lst; j ++) {
            cin >> a[j];
            for(int small = 0; small < j; small ++) {
                int l = lca(a[j], a[small]);
                cnt[a[j]] ++;
                cnt[a[small]] ++;
                cnt[l] -= 2;
            }
        }
    }
    calc(1, 0);

    sort(ans.begin(), ans.end());

    cout << ans.size() << endl;
    for(auto it : ans) {
        cout << it << " ";
    }

    return 0;
}

• Subtask 1: 0 / 8
• Subtask 2: 0 / 15
• Subtask 3: 0 / 7
• Subtask 4: 0 / 29
• Subtask 5: 0 / 16
• Subtask 6: 0 / 25