Submission #1262201

#	Time	Username	Problem	Language	Result	Execution time	Memory
1262201		abdelhakim	Spring cleaning (CEOI20_cleaning)	C++20	18 / 100	1096 ms	30396 KiB

cleaning

#include <bits/stdc++.h>
#define ll long long
#define dbg(x) cerr << #x << ' ' <<  x << endl; 
#define inf 1e18
using namespace std;

void printvec(vector<ll>& vec)
{
  for (auto &&e : vec)
  {
    cout << e << ' ';
  }
  cout << endl;
}
const int maxn = 1e5;
int value[maxn];
int in[maxn];
int out[maxn];
int arr2[maxn];
const int lg=18;
int up[maxn][lg];

ll solve(vector<vector<ll>>& adj, ll node, ll par, ll& ans,vector<pair<ll,ll>>& parr)
{
  if(node!=par && adj[node].size()==1)
  {
    parr[node]={par,1};
    if(node!=0)
    {
      if(parr[node].second==0) ans+=2;
      else ans++;
    }
    return 1;
  }
  ll sm=0;
  for (auto &&e : adj[node])
  {
    if(e==par)continue;
    ll val=solve(adj,e,node,ans,parr);
    sm+=val;
  }
  if(adj[node].size()==1 && node==0) sm++;
  parr[node]={par,sm%2};
  if(node!=0)
  {
    if(parr[node].second==0) ans+=2;
    else ans++;
  }
  return sm;
}
void dfs(ll node, ll par, ll cur,vector<vector<ll>>& adj, vector<pair<ll,ll>>& parr, ll& time)
{
  in[node]=time;
  if(node!=0)
  {
    if(parr[node].second)
    {
      cur++;
    }
    else cur--;
  }
  value[node]=cur;
  for (auto &&e : adj[node])
  {
    if(e==par) continue;
    time++;
    dfs(e,node,cur,adj,parr,time); 
  }
  out[node] = time;
}
void gadup(ll n, vector<pair<ll,ll>>& parr)
{
  for (int i=0;i<n;i++)
  {
    for (int j=0;j<lg;j++)
    {
      if(j==0)
      {
        up[i][j]=parr[i].first;
      }
      else
      {
        up[i][j]=up[up[i][j-1]][j-1];
      }
    }
  }
}
bool islca(ll a, ll b)
{
  if(in[a] <= in[b] && out[b] <= out[a]) return true;
  return false;
}
ll lca(ll u, ll v)
{
  if(islca(u,v)) return u;
  if(islca(v,u)) return v;
  for (int j=lg-1;j>=0;j--)
  {
    if(!(islca(up[u][j],v)))
    {
      u=up[u][j];
    }
  }
  u=up[u][0];
  return u;
}
ll dfs2(ll& ans, ll node, ll par, vector<vector<ll>>& adj)
{
  if(node!=0 && adj[node].size()==1) return arr2[node];
  ll val=arr2[node];
  for (auto &&e : adj[node])
  {
    if(e==par) continue;
    ll qry=dfs2(ans,e,node,adj);
    val+=qry;
    if(qry%2)
    {
      ans+=value[e]-value[node];
    }
  }
  return val;
}

vector<vector<ll>> buildVirtualTree(vector<ll>& nodes) {
    // Sort by Euler tour entry
    sort(nodes.begin(), nodes.end(), [&](int a, int b) { return in[a] < in[b]; });

    // Insert LCAs of consecutive nodes
    int sz = nodes.size();
    for (int i = 0; i < sz-1; i++)
        nodes.push_back(lca(nodes[i], nodes[i+1]));

    // Sort and unique
    sort(nodes.begin(), nodes.end(), [&](int a, int b) { return in[a] < in[b]; });
    nodes.erase(unique(nodes.begin(), nodes.end()), nodes.end());

    // Build virtual tree edges using a stack
    vector<int> stk;
    vector<vector<ll>> vtree(maxn);
    for (int u : nodes) {
        while (!stk.empty() && !islca(stk.back(), u))
            stk.pop_back();
        if (!stk.empty()) {
            // edge from stk.back() -> u in virtual tree
            vtree[stk.back()].push_back(u);
            vtree[u].push_back(stk.back());
        }
        stk.push_back(u);
    }
    return vtree; // returns the list of nodes used in virtual tree
}



int main()
{
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  ll n, q;
  cin>>n>>q;
  for (int i=0;i<maxn;i++)
  {
    arr2[i]=0;
  }
  vector<vector<ll>> adj(n);
  value[0]=0;
  for (int i=0;i<n-1;i++)
  {
    ll u, v;
    cin>>u>>v;
    u--;v--;
    adj[u].push_back(v);
    adj[v].push_back(u);
  }
  ll old=0;
  ll leaves=0;
  for (int i=0;i<n;i++)
  {
    leaves+=adj[i].size()==1;
  }
  vector<pair<ll,ll>> parr(n);
  solve(adj,0,0,old,parr);
  ll time=0;
  dfs(0,0,0,adj,parr,time);
  gadup(n,parr);
  vector<vector<ll>> adj2(n);
  while(q--)
  {
    ll d;
    cin>>d;
    vector<ll> v;
    vector<ll> arr;
    ll ans=old;
    ll val=leaves;
    for (int i=0;i<d;i++)
    {
      ll nd;
      cin>>nd;
      nd--;
      arr.push_back(nd);
    }
    auto comp=[&](ll a, ll b){return in[a]<in[b];};
    sort(arr.begin(), arr.end(),comp);
    ll cur=0;
    for (int i=0;i<d;i++)
    {
      cur++;
      if(i==d-1 || arr[i+1]!=arr[i])
      {
        if(adj[arr[i]].size()==1)
        {
          cur--;
        }
        if(cur%2) v.push_back(arr[i]);
        cur=0;
      }
    }
    val+=v.size();
    if(val%2) cout<<-1<<endl;
    else
    {
      ans+=d;
      vector<ll> v2;
      for (auto &&e : v)
      {
        arr2[e]=1;
        v2.push_back(e);
      }
      v.push_back(0);
      vector<vector<ll>> vtree=buildVirtualTree(v);
      dfs2(ans,0,0,vtree);
      cout << ans << endl;
      for (auto &&e : v2)
      {
        arr2[e]=0;
      }
      
    }
  }
}

• Subtask 1: 0 / 0
• Subtask 2: 9 / 9
• Subtask 3: 9 / 9
• Subtask 4: 0 / 16
• Subtask 5: 0 / 19
• Subtask 6: 0 / 17
• Subtask 7: 0 / 30