Submission #927498

#	Time	Username	Problem	Language	Result	Execution time	Memory
927498		12345678	Spring cleaning (CEOI20_cleaning)	C++17	34 / 100	1069 ms	14172 KiB

cleaning

#include <bits/stdc++.h>

using namespace std;

const int nx=1e5+5;
int n, q, deg[nx], u, v, t, res, rt, cnt[nx];
vector<int> d[nx];

void dfs(int u, int p)
{
    if (d[u].size()==1&&cnt[u]<1) deg[u]++;
    for (auto v:d[u])
    {
        if (v==p) continue;
        dfs(v, u);
        deg[u]+=deg[v];
    }
    if (deg[u]>2) deg[u]=((deg[u]%2)==1)?1:2;
    if (u!=rt) res+=deg[u]; 
}

int main()
{
    cin.tie(NULL)->sync_with_stdio(false);
    cin>>n>>q;
    for (int i=1; i<n; i++) cin>>u>>v, d[u].push_back(v), d[v].push_back(u);
    for (int i=1; i<=n; i++) if (d[i].size()>1) rt=i;
    while (q--)
    {
        for (int i=1; i<=n; i++) deg[i]=cnt[i]=0;
        cin>>t;
        for (int i=0; i<t; i++) cin>>u, deg[u]++, cnt[u]++;
        res=t;
        dfs(rt, rt);
        if ((deg[rt]%2)==0) cout<<res<<'\n';
        else cout<<-1<<'\n';
    }
}

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