Submission #1115235

#	Time	Username	Problem	Language	Result	Execution time	Memory
1115235		PieArmy	Railway (BOI17_railway)	C++17	100 / 100	85 ms	24512 KiB

railway

typedef long long ll;
ll pie(ll army){return (1ll<<army);}
#include <bits/stdc++.h>
#define fr first
#define sc second
#define pb push_back
#define endl '\n'
#define mid ((left+right)>>1)
const ll inf=2000000000000000005;
const int sonsuz=2000000005;
using namespace std;
ll fpow(ll x,ll y,ll m=0){if(y<0){cout<<"powError";return -1;}if(m)x%=m;ll res=1;while(y>0){if(y&1)res*=x;x*=x;if(m){x%=m;res%=m;}y>>=1;}return res;}

int n,m,k;
int tim=0;
int dep[100001],par[100001][17],val[100001],loc[100001];
vector<pair<int,int>>komsu[100001];
vector<int>ans;

void dfs1(int pos){
	for(int i=1;i<17;i++){
		par[pos][i]=par[par[pos][i-1]][i-1];
	}
	loc[pos]=tim++;
	for(auto x:komsu[pos]){
		if(par[pos][0]==x.fr)continue;
		dep[x.fr]=dep[pos]+1;
		par[x.fr][0]=pos;
		dfs1(x.fr);
	}
}

void dfs2(int pos,int ed){
	for(auto x:komsu[pos]){
		if(par[pos][0]==x.fr)continue;
		dfs2(x.fr,x.sc);
		val[pos]+=val[x.fr];
	}
	if(val[pos]>=k)ans.pb(ed);
}

int lca(int a,int b){
	if(dep[a]<dep[b])swap(a,b);
	for(int i=0;i<17;i++){
		if((dep[a]-dep[b])&pie(i)){
			a=par[a][i];
		}
	}
	if(a!=b){
		for(int i=17-1;i>=0;i--){
			if(par[a][i]!=par[b][i]){
				a=par[a][i];
				b=par[b][i];
			}
		}
		a=par[a][0];
	}
	return a;
}

void code(){
	cin>>n>>m>>k;
	for(int i=1;i<n;i++){
		int x,y;cin>>x>>y;
		komsu[x].pb({y,i});
		komsu[y].pb({x,i});
	}
	dfs1(1);
	for(int i=1;i<=m;i++){
		int s;cin>>s;
		vector<int>v;
		for(int j=0;j<s;j++){
			int x;cin>>x;
			v.pb(x);
		}
		sort(v.begin(),v.end(),[&](const int &x,const int &y){
			return loc[x]<loc[y];
		});
		v.pb(v[0]);
		for(int j=0;j<s;j++){
			val[v[j]]++;
			val[lca(v[j],v[j+1])]--;
		}
	}
	dfs2(1,0);
	sort(ans.begin(),ans.end());
	cout<<ans.size()<<endl;
	for(int x:ans)
		cout<<x<<" ";
}

int main(){
	ios_base::sync_with_stdio(false);cin.tie(NULL);
	bool usaco=0;if(usaco){freopen(".in","r",stdin);freopen(".out","w",stdout);}
	int t=1;
	if(!t)cin>>t;
	while(t--){code();cout<<endl;}
	return 0;
}

Compilation message (stderr)

railway.cpp: In function 'int main()':
railway.cpp:94:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   94 |  bool usaco=0;if(usaco){freopen(".in","r",stdin);freopen(".out","w",stdout);}
      |                         ~~~~~~~^~~~~~~~~~~~~~~~~
railway.cpp:94:57: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   94 |  bool usaco=0;if(usaco){freopen(".in","r",stdin);freopen(".out","w",stdout);}
      |                                                  ~~~~~~~^~~~~~~~~~~~~~~~~~~

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