Submission #945769

#	Time	Username	Problem	Language	Result	Execution time	Memory
945769		noyancanturk	Railway (BOI17_railway)	C++17	100 / 100	82 ms	18788 KiB

railway

#ifndef Local
    #pragma GCC optimize("O3,unroll-loops")
    const int lim=1e5+100;
#else
    const int lim=1e3+3;
#endif

const int lglim=18;
    
#include "bits/stdc++.h"
using namespace std;
    
//#define int int64_t
#define pb push_back
    
const int mod=998244353;
//const int mod=(1ll<<61)-1;

using pii=pair<int,int>;

int n,m,k;
int tin[lim],tout[lim],dep[lim],tt=0;
int lift[lglim][lim];
vector<pii>v[lim];
int pare[lim];

inline void tour(int node,int par){
    tin[node]=tt++;
    dep[node]=dep[par]-1;
    lift[0][node]=par;
    int i=1;
    while(i<lglim&&(lift[i][node]=lift[i-1][lift[i-1][node]]))i++;
    for(auto [j,c]:v[node]){
        if(j^par){
            pare[j]=c;
            tour(j,node);
        }
    }
    tout[node]=tt-1;
}

inline int lca(int x,int y){
    if(dep[y]<dep[x])swap(x,y);
    if(dep[x]<dep[y]){
        for(int i=lglim-1;0<=i;i--){
            if(dep[x]+(1<<i)<=dep[y]){
                x=lift[i][x];
            }
            if(dep[x]==dep[y])break;
        }
    }
    if(x==y)return x;
    for(int i=lglim-1;0<=i;i--){
        if(lift[i][x]^lift[i][y]){
            x=lift[i][x];
            y=lift[i][y];
        }
    }
    return lift[0][x];
}

int val[lim];
bool can[lim];
vector<int>ans;


inline int dfs(int node,int par){
    for(auto [j,c]:v[node]){
        if(j^par){
            val[node]+=dfs(j,node);
        }
    }
    if(2*k<=val[node]){
        can[pare[node]]=1;
    }
    return val[node];
}

inline void solve(){
    cin>>n>>m>>k;
    for(int i=1;i<=n-1;i++){
        int x,y;
        cin>>x>>y;
        v[x].pb({y,i});
        v[y].pb({x,i});
    }
    tour(1,0);
    int inds[n+1];
    for(int r=0;r<m;r++){
        int s;
        cin>>s;
        for(int i=0;i<s;i++){
            cin>>inds[i];
        }
        sort(inds,inds+s,[&](int i,int j) -> bool {
            return tin[i]<tin[j];
        });
        inds[s]=inds[0];
        for(int i=0;i<s;i++){
            val[inds[i]]++;
            val[inds[i+1]]++;
            val[lca(inds[i],inds[i+1])]-=2;
        }
    }
    dfs(1,0);
    int cnt=0;
    for(int i=0;i<n;i++){
        if(can[i])cnt++;
    }
    cout<<cnt<<"\n";
    for(int i=0;i<n;i++)if(can[i])cout<<i<<" ";
}
    
signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
#ifdef Local  
    freopen(".in","r",stdin);
    freopen(".out","w",stdout);
#else

#endif
    int t=1;
    //cin>>t;
    while (t--)
    {
        solve();
    }
}

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