Submission #553396

#	Time	Username	Problem	Language	Result	Execution time	Memory
553396		new_acc	Railway (BOI17_railway)	C++14	100 / 100	147 ms	26384 KiB

railway

#include<bits/stdc++.h>
#define fi first
#define se second
#define pitem item*
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<ll> vl;
const int N=1e5+10;
const int SS=1<<19;
const int INFi=2e9;
const ll INFl=1e13;
const ll mod2=998244353;
const ll mod=1e9+7;
const ll mod3=1000696969;
const ll p=70032301;
const ull p2=913;
const int L=17;
int n,m,k,oj[N],il[N],jump[N][L+1],pre[N],l,dep[N],dod[N];
pair<int,int> w[N];
vi graf[N];
void dfs(int v,int o){
	jump[v][0]=o;
	for(int i=1;i<=L;i++) jump[v][i]=jump[jump[v][i-1]][i-1];
	pre[v]=++l;
	dep[v]=dep[o]+1;
	for(auto u:graf[v]){
		if(u==o) continue;
		dfs(u,v);
	}
}
void dfs2(int v,int o){
	il[v]+=dod[v];
	for(auto u:graf[v]){
		if(u==o) continue;
		dfs2(u,v);
		il[v]+=il[u];
	}
}
int lca(int a,int b){
	if(dep[a]<dep[b]) swap(a,b);
	for(int i=L;i>=0;i--) if(dep[jump[a][i]]>=dep[b]) a=jump[a][i];
	if(a==b) return a;
	int res=0;
	for(int i=L;i>=0;i--){
		if(jump[a][i]==jump[b][i]) res=jump[a][i];
		else a=jump[a][i],b=jump[b][i];
	}
	return res;
}
void solve(){
	cin>>n>>m>>k;
	k<<=1;
	for(int a,b,i=1;i<n;i++){
		cin>>a>>b;
		graf[a].push_back(b),graf[b].push_back(a);
		w[i]={a,b};
	}
	dfs(1,1);
	for(int i=1;i<n;i++){
		if(dep[w[i].fi]<dep[w[i].se]) oj[w[i].se]=i;
		else oj[w[i].fi]=i;
	}
	for(int i=1;i<=m;i++){
		int xd;
		cin>>xd;
		vector<pair<int,int> >v;
		while(xd--){
			int curr;
			cin>>curr;
			v.push_back({pre[curr],curr});
		}
		sort(v.begin(),v.end());
		v.push_back(v[0]);
		for(int j=0;j<v.size()-1;j++) dod[v[j].se]++,dod[v[j+1].se]++,dod[lca(v[j].se,v[j+1].se)]-=2;
	}
	dfs2(1,1);
	vi res;
	for(int i=2;i<=n;i++) if(il[i]>=k) res.push_back(oj[i]);
	cout<<res.size()<<"\n";
	sort(res.begin(),res.end());
	for(auto u:res) cout<<u<<" ";
	cout<<"\n";
}
int main(){
	ios_base::sync_with_stdio(0),cin.tie(0);
	solve();
}

Compilation message (stderr)

railway.cpp: In function 'void solve()':
railway.cpp:76:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   76 |   for(int j=0;j<v.size()-1;j++) dod[v[j].se]++,dod[v[j+1].se]++,dod[lca(v[j].se,v[j+1].se)]-=2;
      |               ~^~~~~~~~~~~

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