Submission #465324

#	Time	Username	Problem	Language	Result	Execution time	Memory
465324		Khizri	Railway (BOI17_railway)	C++17	100 / 100	282 ms	54768 KiB

railway

#include <bits/stdc++.h>
using namespace std;
//------------------------------DEFINE------------------------------
//******************************************************************
#define IOS ios_base::sync_with_stdio(false); cin.tie(0),cout.tie(0)
#define ll long long
#define pb push_back		 
#define F first																 
#define S second 															 
#define INF 1e18
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define pii pair<int,int>
#define pll pair<ll,ll>
#define OK cout<<"Ok"<<endl;
#define MOD (ll)(1e9+7)
#define endl "\n"
//******************************************************************
//----------------------------FUNCTION------------------------------
//******************************************************************
ll gcd(ll a,ll b){
	if(a>b) swap(a,b);
	if(a==0) return a+b;
	return gcd(b%a,a);
}
ll lcm(ll a,ll b){
	return a/gcd(a,b)*b;
}
bool is_prime(ll n){
	ll k=sqrt(n);
	if(n==2) return true;
	if(n<2||n%2==0||k*k==n) return false;
	for(int i=3;i<=k;i+=2){
		if(n%i==0){
			return false;
		}
	}
	return true;
}
//*****************************************************************
//--------------------------MAIN-CODE------------------------------
const int mxn=1e5+5,lg=30;
int t=1,n,m,k,x,y,up[mxn][lg],tin[mxn],tout[mxn],timer,node[mxn],color[mxn],say[mxn],sum[mxn];
vector<int>vt[mxn];
vector<int>arr[mxn];
map<pll,int>mp;
set<int>ans;
void dfs(int u,int p){
	tin[u]=++timer;
	up[u][0]=p;
	for(int i=1;i<lg;i++){
		up[u][i]=up[up[u][i-1]][i-1];
	}
	for(int v:vt[u]){
		if(v!=p){
			dfs(v,u);
		}
	}
	tout[u]=++timer;
}
bool funk(int u,int v){
	return tin[u]<=tin[v]&&tout[u]>=tout[v];
}
int lca(int u,int v){
	if(funk(u,v)){
		return u;
	}
	for(int i=lg-1;i>=0;i--){
		if(!funk(up[u][i],v)){
			u=up[u][i];
		}
	}
	return up[u][0];
}
void dfs_sum(int u,int p){
	for(int v:vt[u]){
		if(v!=p){
			dfs_sum(v,u);
			sum[u]+=sum[v];
		}
	}
	for(int v:vt[u]){
		if(v!=p){
			if(sum[v]>=2*k){
				ans.insert(mp[{u,v}]);
			}
		}
	}
}
bool f(int u,int v){
	return tin[u]<tin[v];
}
void solve(){
	cin>>n>>m>>k;
	for(int i=1;i<n;i++){
		cin>>x>>y;
		vt[x].pb(y);
		vt[y].pb(x);
		mp[{x,y}]=i;
		mp[{y,x}]=i;
	}
	dfs(1,1);
	for(int qq=1;qq<=m;qq++){
		cin>>x;
		for(int i=1;i<=x;i++){
			cin>>node[i];
		}
		sort(node+1,node+x+1,f);
		for(int i=2;i<=x;i++){
			int q=lca(node[i-1],node[i]);
			int u=node[i-1],v=node[i];
			sum[u]++,sum[v]++;
			sum[q]-=2;
		}
		int q=lca(node[1],node[x]);
		int u=node[1],v=node[x];
		sum[u]++,sum[v]++;
		sum[q]-=2;
	}
	dfs_sum(1,-1);
	cout<<ans.size()<<endl;
	for(int v:ans){
		cout<<v<<' ';
	}
	cout<<endl;
}
int main(){
	IOS;
	//cin>>t;
	while(t--){
		solve();
	}
	return 0;
}

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