Submission #1004403

#	Time	Username	Problem	Language	Result	Execution time	Memory
1004403		ayankarimova	Railway (BOI17_railway)	C++14	30 / 100	1061 ms	108252 KiB

railway

#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define ll long long
const ll sz=1e5+5;
ll pre[sz], tt, pos[sz], in[sz], root, p[sz], lvl[sz], dp[sz][100], ln, mx;
vector<ll>g[sz], vec={0};
    set<ll>s;
/*
{} []
*/
void dfs1(ll u, ll par)
{
    vec.push_back(u);
    pos[u]=++tt;
    for(auto v:g[u]){
        if(v!=par){
            dfs1(v, u);
        }
    }
}
void dfs2(ll u, ll par)
{
    lvl[u]=lvl[par]+1;
    dp[u][0]=par;
    for(int i=1; i<ln; i++){
        dp[u][i]=dp[dp[u][i-1]][i-1];
    }
    for(auto v:g[u]){
        if(v!=par){
            p[v]=u;
            dfs2(v, u);
        }
    }
}
ll lca(ll u, ll v)
{
    if(lvl[u]<lvl[v]) swap(u, v);
    ll dif=lvl[u]-lvl[v];
    for(int i=0; i<ln; i++){
        if(dif&(1<<i)){
            u=dp[u][i];
        }
    }
    if(u==v) return u;
    for(int i=ln-1; i>=0; i--){
        if(dp[u][i]!=dp[v][i]){
            u=dp[u][i];
            v=dp[v][i];
        }
    }
    return dp[u][0];
}
int main()
{
    ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    ll n, m, kk;
    cin>>n>>m>>kk;
    map<pair<ll, ll>, ll>m1;
    for(int i=1; i<n; i++){
        ll a, b;
        cin>>a>>b;
        g[a].push_back(b);
        g[b].push_back(a);
        m1[{a, b}]=i;
        m1[{b, a}]=i;
        in[a]++; in[b]++;
    }
    for(int i=1; i<=n; i++){
        if(in[i]==1) root=i;
        mx=max(mx, in[i]);
    }
    if(mx>2){
        map<pair<ll, ll> , ll>mp;
        dfs2(1, 0);
        ln=(ceil)(log2(n));
        dfs2(1, 0);
        for(int i=1; i<=m; i++){
            ll num;
            cin>>num;
            ll k[num+1];
            for(int j=1; j<=num; j++){
                cin>>k[j];
            }
            set<pair<ll, ll>>cur;
            for(int j=2; j<=num; j++){
                ll x=k[j-1], y=k[j];
                ll l=lca(x, y);
                //cout<<x<<' '<<y<<' '<<l<<endl;

                while(y!=l){
                    ll a=y, b=p[y];
                    ll c=a, d=b;
                    //cout<<a<<' '<<b<<endl;
                    if(c>d) swap(c, d);
                    cur.insert({c, d});
                    y=b;
                }
                while(x!=l){
                    ll a=x, b=p[x];
                    ll c=a, d=b;
                    if(c>d) swap(c, d);
                    cur.insert({c, d});
                    x=b;
                }
            }
            for(auto i:cur){
                mp[{i.first, i.second}]++;
            }
        }
        for(auto i:mp){
            if(i.second>=kk){
                s.insert(m1[{i.first.first, i.first.second}]);
            }
        }
        cout<<s.size()<<endl;
        for(auto i:s) cout<<i<<' ';
        return 0;
    }
    map<ll, ll>mp;
    dfs1(root, 0);
    for(int i=1; i<=m; i++){
        ll num;
        cin>>num;
        ll k[num+1];
        for(int j=1; j<=num; j++){
            cin>>k[j];
        }
        for(int j=2; j<=num; j++){
            ll x=k[j-1], y=k[j];
            ll a=pos[x], b=pos[y];
            if(a>b) swap(a, b);
            pre[a]++; pre[b]--;
        }
    }
    for(int i=1; i<n; i++){
        pre[i]+=pre[i-1];
        mp[m1[{vec[i], vec[i+1]}]]+=pre[i];
        //cout<<p[i]<<' ';
    }
    for(auto i:mp){
        if(i.second>=kk){
            s.insert(i.first);
        }
    }
    cout<<s.size()<<endl;
    for(auto i:s) cout<<i<<' ';
}
/*
{} []
4 3 3
2 1
1 4
4 3
3 1 2 3
2 1 4
2 2 3
*/

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