Submission #719380

#	Time	Username	Problem	Language	Result	Execution time	Memory
719380		n0sk1ll	Railway (BOI17_railway)	C++14	100 / 100	182 ms	29632 KiB

railway

#include <bits/stdc++.h>
 
#define FAST ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);cerr.tie(0)
#define mp make_pair
#define xx first
#define yy second
#define pb push_back
#define pf push_front
#define popb pop_back
#define popf pop_front
#define all(x) x.begin(),x.end()
#define ff(i,a,b) for (int i = a; i < b; i++)
#define fff(i,a,b) for (int i = a; i <= b; i++)
#define bff(i,a,b) for (int i = b-1; i >= a; i--)
#define bfff(i,a,b) for (int i = b; i >= a; i--)
 
using namespace std;
long double typedef ld;
unsigned int typedef ui;
long long int typedef li;
pair<int,int> typedef pii;
pair<li,li> typedef pli;
pair<ld,ld> typedef pld;
vector<vector<int>> typedef graph;
unsigned long long int typedef ull;
//const int mod = 998244353;
const int mod = 1000000007;
 
 
 
 
 
 
 
//Note to self: Check for overflow
 
graph g(100005);
int up[18][100005],add[18][100005];
int tin[100005],tout[100005],vcvor[100005];
int VREME=0;
 
void dfs(int p, int q)
{
    up[0][p]=q,tin[p]=++VREME,vcvor[VREME]=p;
    for (auto it : g[p]) if (it!=q) dfs(it,p);
    tout[p]=VREME;
}
 
void build(int n)
{
    ff(k,1,18) fff(i,1,n) up[k][i]=up[k-1][up[k-1][i]];
}
 
bool anc(int a, int b)
{
    return tin[a]<=tin[b] && tout[a]>=tout[b];
}
 
int Lca(int a, int b)
{
    bff(k,0,18) if (!anc(up[k][a],b)) a=up[k][a];
    if (!anc(a,b)) a=up[0][a];
    return a;
}
 
void append(int a, int b) //b MORA biti parent od a - ovo znaci da razmatramo sve cvorove od a nagore do b.
{
    bff(k,0,18) if (!anc(up[k][a],b)) add[k][a]++,a=up[k][a];
    if (!anc(a,b)) add[0][a]++;
}
 
void razmotri(int a, int b)
{
    //cout<<a<<" "<<b<<": "<<Lca(a,b)<<endl;
    int c=Lca(a,b);
    append(a,c),append(b,c);
}
 
void deliftuj(int n)
{
    bff(k,0,17) fff(i,1,n) add[k][i]+=add[k+1][i],add[k][up[k][i]]+=add[k+1][i];
}
 
vector<pii> eds;
 
int main()
{
    FAST;
 
    int n,m,request; cin>>n>>m>>request;
    ff(i,1,n) {int u,v; cin>>u>>v; g[u].pb(v),g[v].pb(u); eds.pb({u,v});}
    dfs(1,0),tout[0]=VREME,build(n);
 
    while (m--)
    {
        int s; cin>>s;
        vector<pii> v(s);
        ff(i,0,s) cin>>v[i].yy,v[i].xx=tin[v[i].yy];
        sort(all(v));
        ff(i,1,s) razmotri(v[i-1].yy,v[i].yy);
        razmotri(v[s-1].yy,v[0].yy);
    }
 
    /*ff(k,0,18)
    {
        cout<<k<<": ";
        fff(i,1,n) cout<<add[k][i]<<" ";
        cout<<endl;
    } cout<<endl;*/
 
    deliftuj(n);
    vector<int> ans;
    int INDEXLOL=0;
    for (auto it : eds)
    {
        ++INDEXLOL;
        if (anc(it.xx,it.yy)) swap(it.xx,it.yy);
        if (add[0][it.xx]>=2*request) ans.pb(INDEXLOL);
    }
 
    cout<<(int)ans.size()<<"\n";
    for (auto it : ans) cout<<it<<" ";
 
    /*while (true)
    {
        int a,b; cin>>a>>b;
        cout<<"lca: "<<Lca(a,b)<<endl;
        cout<<"parent("<<a<<","<<b<<") = "<<anc(a,b)<<endl;
    }*/
}
 
//Note to self: Check for overflow

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