Submission #695175

#	Time	Username	Problem	Language	Result	Execution time	Memory
695175		amirhoseinfar1385	Railway (BOI17_railway)	C++17	100 / 100	184 ms	29248 KiB

railway

#include<bits/stdc++.h>
using namespace std;
int n,m,k;
const int maxn=100000+5;
vector<pair<int,int>>adj[maxn];
struct node{
	int res;
	map<int,int>mp;
	node(){
		res=0;
	}
};
node dp[maxn];
int allv[maxn];
vector<int>mainres;

void merge(int u,int v){
	int fu=u,fv=v;
	if(dp[u].mp.size()<dp[v].mp.size()){
		swap(u,v);
	}	
	dp[u].res+=dp[v].res;
	for(auto x:dp[v].mp){
		dp[u].mp[x.first]+=x.second;
		if(x.second!=allv[x.first]&&dp[u].mp[x.first]==allv[x.first]){
			dp[u].res++;
		}
	}
	dp[v].mp.clear();
	if(u!=fu){
		swap(dp[fu],dp[u]);
	}
}

void solve(int u,int par,int w){
	for(auto x:adj[u]){
		if(x.first!=par){
			solve(x.first,u,x.second);
			merge(u,x.first);
		}
	}
//	cout<<u<<" "<<dp[u].res<<"\n";
	int q=dp[u].mp.size();
	q-=dp[u].res;
	if(u!=1&&q>=k){
		mainres.push_back(w);
	}
}

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>m>>k;
	for(int i=0;i<n-1;i++){
		int u,v;
		cin>>u>>v;
		adj[u].push_back(make_pair(v,i+1));
		adj[v].push_back(make_pair(u,i+1));
	}
	for(int i=0;i<m;i++){
		cin>>allv[i];
		for(int j=0;j<allv[i];j++){
			int d;
			cin>>d;
			dp[d].mp[i]=1;
			if(allv[i]==1){
				dp[d].res++;
			}
		}
	}
	solve(1,0,-1);
	cout<<((int)mainres.size())<<"\n";
	sort(mainres.begin(),mainres.end());
	for(auto x:mainres){
		cout<<x<<" ";
	}
	cout<<"\n";
}

Compilation message (stderr)

railway.cpp: In function 'void merge(int, int)':
railway.cpp:18:11: warning: unused variable 'fv' [-Wunused-variable]
   18 |  int fu=u,fv=v;
      |           ^~

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